Pub Date : 2025-02-01DOI: 10.1016/j.orgel.2024.107175
Emmanuel Santos Moraes, José Carlos Germino, Luiz Pereira
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Although OLEDs are widely employed nowadays for display technology devices, their application for room-lighting illumination remains a challenge due to the cost-effectiveness issues, mainly related to device fabrication. In this sense, the present study investigates the optimization of blue-emitting TADF (DMOC-DPS) and yellow-emitting TADF (TXO-TPA) compounds in solution-processed OLEDs to achieve efficient white light emission in a two-organic layer device. Four different host materials were studied, aiming to balance the charge mobility of holes and electrons. The host materials used include (in %wt.) a 1:1 mixture of mCP and DPEPO (HOST1), a 3:2 mixture of PVK and DPEPO (HOST2), a 3:2 mixture of PVK and mCP (HOST3), and a 3:2 mixture of PVK and butyl-PBD (HOST4). The experimental results obtained from the solution-processed OLEDs indicate that DMOC-DPS is predominantly a hole transport material, and hosts with predominantly n-type character, such as HOST1 and HOST4, resulting in the most efficient white-OLEDs by the most balanced charge mobility. With structure optimization, WOLEDs achieved 6.43 % EQE with a brightness of 2621 cd/m2 (not integrated) and 6.06 % EQE with a brightness of 1986 cd/m2 for HOST4 and HOST1, respectively. The emission characteristics were influenced by host materials characteristics, with blue and yellow emissions being fine-tuned to produce complementary colors. This study highlights the critical role of charge mobility balance in the emissive layer and demonstrates the potential of independently optimizing blue and yellow TADF components for high-performance WOLEDs suitable for indoor lighting applications.
{"title":"Approaches for white organic light-emitting diode via solution-processed blue and yellow TADF emitters: Charge balance and host-guest interactions in a single emission layer","authors":"Emmanuel Santos Moraes, José Carlos Germino, Luiz Pereira","doi":"10.1016/j.orgel.2024.107175","DOIUrl":"10.1016/j.orgel.2024.107175","url":null,"abstract":"<div><div><span><figure><span><img><ol><li><span><span>Download: <span>Download high-res image (233KB)</span></span></span></li><li><span><span>Download: <span>Download full-size image</span></span></span></li></ol></span></figure></span>Although OLEDs are widely employed nowadays for display technology devices, their application for room-lighting illumination remains a challenge due to the cost-effectiveness issues, mainly related to device fabrication. In this sense, the present study investigates the optimization of blue-emitting TADF (DMOC-DPS) and yellow-emitting TADF (TXO-TPA) compounds in solution-processed OLEDs to achieve efficient white light emission in a two-organic layer device. Four different host materials were studied, aiming to balance the charge mobility of holes and electrons. The host materials used include (in %wt.) a 1:1 mixture of mCP and DPEPO (<strong>HOST1</strong>), a 3:2 mixture of PVK and DPEPO (<strong>HOST2</strong>), a 3:2 mixture of PVK and mCP (<strong>HOST3</strong>), and a 3:2 mixture of PVK and butyl-PBD (<strong>HOST4</strong>). The experimental results obtained from the solution-processed OLEDs indicate that DMOC-DPS is predominantly a hole transport material, and hosts with predominantly n-type character, such as <strong>HOST1</strong> and <strong>HOST4</strong>, resulting in the most efficient white-OLEDs by the most balanced charge mobility. With structure optimization, WOLEDs achieved 6.43 % EQE with a brightness of 2621 cd/m<sup>2</sup> (not integrated) and 6.06 % EQE with a brightness of 1986 cd/m<sup>2</sup> for <strong>HOST4</strong> and <strong>HOST1</strong>, respectively. The emission characteristics were influenced by host materials characteristics, with blue and yellow emissions being fine-tuned to produce complementary colors. This study highlights the critical role of charge mobility balance in the emissive layer and demonstrates the potential of independently optimizing blue and yellow TADF components for high-performance WOLEDs suitable for indoor lighting applications.</div></div>","PeriodicalId":399,"journal":{"name":"Organic Electronics","volume":"137 ","pages":"Article 107175"},"PeriodicalIF":2.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143172723","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.orgel.2024.107183
Gulnur Akhtanova , Hryhorii P. Parkhomenko , Joachim Vollbrecht , Andrii I. Mostovyi , Nora Schopp , Viktor Brus
This study extends the analytical model of surface recombination in organic solar cells with an intrinsic active bulk-heterojunction layer. The key finding of the developed multi-mechanism recombination model accounting for the intrinsic active layer is that the slope of VOC vs. ln(Light Intensity) cannot be lower than 1.0 kT/q even at the extremely high concentrations of surface traps. We revealed the difference in recombination-related parameters determined in the scope of the multi-mechanism recombination model for the doped or intrinsic active layer and highlighted the importance of identifying the doping level of the active layer material. This is demonstrated by a synergy of comprehensive simulation and experimental analysis of organic solar cells with donor: acceptor blends: (PM6:Y6, PTB7-Th:COTIC-4F, PTB7-Th:O-IDTBR and PTB7-Th:ITIC-4F).
{"title":"Surface recombination in organic solar cells: Intrinsic vs. doped active layer","authors":"Gulnur Akhtanova , Hryhorii P. Parkhomenko , Joachim Vollbrecht , Andrii I. Mostovyi , Nora Schopp , Viktor Brus","doi":"10.1016/j.orgel.2024.107183","DOIUrl":"10.1016/j.orgel.2024.107183","url":null,"abstract":"<div><div>This study extends the analytical model of surface recombination in organic solar cells with an intrinsic active bulk-heterojunction layer. The key finding of the developed multi-mechanism recombination model accounting for the intrinsic active layer is that the slope of <em>V</em><sub><em>OC</em></sub> vs. ln(Light Intensity) cannot be lower than 1.0 kT<em>/q</em> even at the extremely high concentrations of surface traps. We revealed the difference in recombination-related parameters determined in the scope of the multi-mechanism recombination model for the doped or intrinsic active layer and highlighted the importance of identifying the doping level of the active layer material. This is demonstrated by a synergy of comprehensive simulation and experimental analysis of organic solar cells with donor: acceptor blends: (PM6:Y6, PTB7-Th:COTIC-4F, PTB7-Th:O-IDTBR and PTB7-Th:ITIC-4F).</div></div>","PeriodicalId":399,"journal":{"name":"Organic Electronics","volume":"137 ","pages":"Article 107183"},"PeriodicalIF":2.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143172724","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-31DOI: 10.1016/j.orgel.2025.107206
Yaoyao Song, Huiyin Zhang, Shixian Huang, Yunzhao Sun, Mengfan Liu, Kai Pang
The commercialization of perovskite solar cells (PSCs) technology is in full swing, but the ecotoxicity of the solvents involved in perovskite processing remains a barrier. Herein, a low-toxicity 1,3-dimethyl-2-imidazolidinone(dimethyl sulfoxide) solvent system, abbreviated as DMI(DMSO), has been designed to support the green fabrication of perovskite films and PSCs. Both DMI and DMSO can be proposed as less-toxic solvents. By optimizing the volume ratio of DMSO cosolvent in DMI(DMSO) solvent system, the morphologies, optical properties and photovoltaic performance of perovskite films can be well modulated. The delivered planar PSCs achieved a best power conversion efficiency of up to 20.24 %, comparable to those of devices based on the traditional solvent systems. This work provides a feasible way to produce scalable PSCs with high efficiency using an environmentally benign solvent system.
{"title":"A low-toxicity precursor solvent system enabled green fabrication of high-performance perovskite solar cells","authors":"Yaoyao Song, Huiyin Zhang, Shixian Huang, Yunzhao Sun, Mengfan Liu, Kai Pang","doi":"10.1016/j.orgel.2025.107206","DOIUrl":"10.1016/j.orgel.2025.107206","url":null,"abstract":"<div><div>The commercialization of perovskite solar cells (PSCs) technology is in full swing, but the ecotoxicity of the solvents involved in perovskite processing remains a barrier. Herein, a low-toxicity 1,3-dimethyl-2-imidazolidinone(dimethyl sulfoxide) solvent system, abbreviated as DMI(DMSO), has been designed to support the green fabrication of perovskite films and PSCs. Both DMI and DMSO can be proposed as less-toxic solvents. By optimizing the volume ratio of DMSO cosolvent in DMI(DMSO) solvent system, the morphologies, optical properties and photovoltaic performance of perovskite films can be well modulated. The delivered planar PSCs achieved a best power conversion efficiency of up to 20.24 %, comparable to those of devices based on the traditional solvent systems. This work provides a feasible way to produce scalable PSCs with high efficiency using an environmentally benign solvent system.</div></div>","PeriodicalId":399,"journal":{"name":"Organic Electronics","volume":"139 ","pages":"Article 107206"},"PeriodicalIF":2.7,"publicationDate":"2025-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143352713","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Thermally activated delayed fluorescence (TADF) has gained significant attention as a key mechanism in developing highly efficient organic light-emitting diodes (OLEDs). This review consolidates recent advancements in the theoretical exploration of TADF mechanisms, emphasizing the intricate donor-acceptor (D-A) interactions, the influence of various donor groups on the optical properties, and the behavior of luminescence across different phases. Employing a multiscale simulation, which encompasses density functional theory (DFT) and time-dependent DFT (TD-DFT), this paper elucidates the electroluminescence mechanisms of TADF molecules in both amorphous and crystalline states. The study highlights the significant impact of solid-state interactions on the luminescent properties of TADF materials, offering a comprehensive understanding of the structure-property relationships. These theoretical insights provide a robust foundation for designing next-generation TADF materials with optimized performance, addressing the existing challenges in achieving efficient blue and red light emitters for practical applications in OLED technology. Through this review, we aim to present a coherent overview of the current state of TADF research, identify the critical factors influencing luminescence, and propose strategic directions for future research to further enhance the efficacy and applicability of TADF-based OLEDs.
{"title":"Luminescence properties and mechanism studies of thermally activated delayed fluorescence molecules","authors":"Zhimin Wu, Xiaofei Wang, Rui Li, Jiaxin Zhou, Ying Cao, Yuzhi Song, Jianzhong Fan, Chuan-Kui Wang, Lili Lin, Zhongjie Wang","doi":"10.1016/j.orgel.2025.107205","DOIUrl":"10.1016/j.orgel.2025.107205","url":null,"abstract":"<div><div>Thermally activated delayed fluorescence (TADF) has gained significant attention as a key mechanism in developing highly efficient organic light-emitting diodes (OLEDs). This review consolidates recent advancements in the theoretical exploration of TADF mechanisms, emphasizing the intricate donor-acceptor (D-A) interactions, the influence of various donor groups on the optical properties, and the behavior of luminescence across different phases. Employing a multiscale simulation, which encompasses density functional theory (DFT) and time-dependent DFT (TD-DFT), this paper elucidates the electroluminescence mechanisms of TADF molecules in both amorphous and crystalline states. The study highlights the significant impact of solid-state interactions on the luminescent properties of TADF materials, offering a comprehensive understanding of the structure-property relationships. These theoretical insights provide a robust foundation for designing next-generation TADF materials with optimized performance, addressing the existing challenges in achieving efficient blue and red light emitters for practical applications in OLED technology. Through this review, we aim to present a coherent overview of the current state of TADF research, identify the critical factors influencing luminescence, and propose strategic directions for future research to further enhance the efficacy and applicability of TADF-based OLEDs.</div></div>","PeriodicalId":399,"journal":{"name":"Organic Electronics","volume":"139 ","pages":"Article 107205"},"PeriodicalIF":2.7,"publicationDate":"2025-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143283856","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-31DOI: 10.1016/j.orgel.2025.107207
Minghui Huang , Xueting Yi , Zekun Liu , Mengan Zhao , Jiang Wu , Yingying Fu , Zhiyuan Xie
The additives play a vital role in both photovoltaic performance and device stability of organic solar cells (OSCs). Although solvent additives have been extensively utilized in conventional OSC structures to adjust film morphology and regulate crystallization behavior of photoactive materials, their attempt and specific roles in inverted OSCs remain rarely explored. Herein, a kind of halogen-free and volatile solvent additive methyl benzoate (MB) is selected for optimization of the inverted OSCs. It is found that MB could produce distinct positive interaction with L8-BO acceptors, leading to enhanced molecular crystallization and appropriate microstructure in PM6:L8-BO active layers. In addition, the MB-processed PM6:L8-BO films exhibit an optimized vertical phase distribution driven by differences of miscibility between components. The improved horizontal and vertical morphology facilitates charge transport and suppresses charge recombination in the resultant inverted OSCs. Consequently, the power conversion efficiency (PCE) increases from 15.88 % to 17.08 %. Furthermore, the volatile MB with a low boiling point and high vapor pressure could prevent residual in active layers and avoid thermal degradation of OSCs. Benefiting from synergistic effects of the positive volatility and improved acceptor crystallinity, the MB-processed devices demonstrate enhanced thermal stability compared to the control devices. This work highlights the potential of volatile solvent additives for fabricating efficient and stable inverted OSC devices.
{"title":"Regulation of film morphology and vertical phase separation for inverted organic solar cells via a volatile solvent additive","authors":"Minghui Huang , Xueting Yi , Zekun Liu , Mengan Zhao , Jiang Wu , Yingying Fu , Zhiyuan Xie","doi":"10.1016/j.orgel.2025.107207","DOIUrl":"10.1016/j.orgel.2025.107207","url":null,"abstract":"<div><div>The additives play a vital role in both photovoltaic performance and device stability of organic solar cells (OSCs). Although solvent additives have been extensively utilized in conventional OSC structures to adjust film morphology and regulate crystallization behavior of photoactive materials, their attempt and specific roles in inverted OSCs remain rarely explored. Herein, a kind of halogen-free and volatile solvent additive methyl benzoate (MB) is selected for optimization of the inverted OSCs. It is found that MB could produce distinct positive interaction with L8-BO acceptors, leading to enhanced molecular crystallization and appropriate microstructure in PM6:L8-BO active layers. In addition, the MB-processed PM6:L8-BO films exhibit an optimized vertical phase distribution driven by differences of miscibility between components. The improved horizontal and vertical morphology facilitates charge transport and suppresses charge recombination in the resultant inverted OSCs. Consequently, the power conversion efficiency (PCE) increases from 15.88 % to 17.08 %. Furthermore, the volatile MB with a low boiling point and high vapor pressure could prevent residual in active layers and avoid thermal degradation of OSCs. Benefiting from synergistic effects of the positive volatility and improved acceptor crystallinity, the MB-processed devices demonstrate enhanced thermal stability compared to the control devices. This work highlights the potential of volatile solvent additives for fabricating efficient and stable inverted OSC devices.</div></div>","PeriodicalId":399,"journal":{"name":"Organic Electronics","volume":"139 ","pages":"Article 107207"},"PeriodicalIF":2.7,"publicationDate":"2025-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140501","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-16DOI: 10.1016/j.orgel.2025.107204
Edoardo Stanzani , Stefano Sem , Simon Züfle , Beat Ruhstaller , Sandra Jenatsch
Thermally activated delayed fluorescence (TADF) emitters attract interest as organic light-emitting diode (OLED) materials with potentially 100 % internal quantum efficiency (IQE). Their application in commercial displays is still hindered due to the not yet sufficient operational stability. We analyze the degradation mechanism in a TADF OLED by combining intermittent electro-optical characterization with device simulations. Evidence for the generation of trap states is found in capacitance-voltage (C-V) measurements. To explain both the C-V as well as the current-voltage and the capacitance-frequency evolution during prolonged operation times, at least two types of trap states are necessary. Device simulations are used to assess their location within the multilayer structure. It is found that both hole and electron traps at the HTL/EML interface can explain the experimental data. A quantitative comparison of simulations and experimental data reveal a hole and electron trap density of 8 ∙ 1018 cm−3 and 8 ∙ 1017 cm−3, respectively, at LT80 (the time at which the luminance has dropped to 80 % of its initial value). The main driver for the current efficiency decrease are the hole traps inside the HTL. The findings unravel the weak points in the TADF OLED and thereby guide further development to enhance device stability.
{"title":"Evidence for localized trap formation during TADF OLED degradation","authors":"Edoardo Stanzani , Stefano Sem , Simon Züfle , Beat Ruhstaller , Sandra Jenatsch","doi":"10.1016/j.orgel.2025.107204","DOIUrl":"10.1016/j.orgel.2025.107204","url":null,"abstract":"<div><div>Thermally activated delayed fluorescence (TADF) emitters attract interest as organic light-emitting diode (OLED) materials with potentially 100 % internal quantum efficiency (IQE). Their application in commercial displays is still hindered due to the not yet sufficient operational stability. We analyze the degradation mechanism in a TADF OLED by combining intermittent electro-optical characterization with device simulations. Evidence for the generation of trap states is found in capacitance-voltage (C-V) measurements. To explain both the C-V as well as the current-voltage and the capacitance-frequency evolution during prolonged operation times, at least two types of trap states are necessary. Device simulations are used to assess their location within the multilayer structure. It is found that both hole and electron traps at the HTL/EML interface can explain the experimental data. A quantitative comparison of simulations and experimental data reveal a hole and electron trap density of 8 ∙ 10<sup>18</sup> cm<sup>−3</sup> and 8 ∙ 10<sup>17</sup> cm<sup>−3</sup>, respectively, at LT80 (the time at which the luminance has dropped to 80 % of its initial value). The main driver for the current efficiency decrease are the hole traps inside the HTL. The findings unravel the weak points in the TADF OLED and thereby guide further development to enhance device stability.</div></div>","PeriodicalId":399,"journal":{"name":"Organic Electronics","volume":"139 ","pages":"Article 107204"},"PeriodicalIF":2.7,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140499","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-16DOI: 10.1016/j.orgel.2025.107197
Nouman Ahmed , Manzoor Hussain , Aumber abbas , Tauqeer Haidar Qamar , Sibt ul Hassan , Pengkun Xia , Lei Ma , Xiaohui Gao , Lianwen Deng
In this work, a series of nitrogen and sulfur co-doped carbon dots (CDs) were synthesized with high photoluminescence quantum yields (PLQYs) and outstanding thermal stability. With the reaction solvent changing from water, ethanol, methanol, and dimethylformamide (DMF), a significant fluorescence emission with PLQY improvement from 42 %, 33 %, 25 %, and 18 %, respectively, accompanied by a red shift from 430 to 590 nm, (the color changes from blue, green, yellow, and red respectively). Simultaneously, excellent fluorescence stability can also be obtained across temperatures ranging from 15 to 95 °C. Combined with the density functional calculations (DFT) results, the underlying mechanism investigation reveals that the color change of fluorescence emission was probably induced by the increased particle size of CDs and increased graphitic N content. The enhanced thermal stability is induced by the presence of stable surface functional groups, including C=O, C=N, C=S, and -NH, among others, contributing to improved hydrophilicity, regulated particle aggregation, and mitigated thermal oxidation by limiting oxygen diffusion to fluorescent hubs. Notably, the obtained outstanding optical properties finally render these multicolor CDs suitable for information encryption and anti-counterfeiting applications.
{"title":"Nitrogen and sulfur Co-doped carbon dots with excellent fluorescent thermal stability for anti-counterfeiting and information encryption","authors":"Nouman Ahmed , Manzoor Hussain , Aumber abbas , Tauqeer Haidar Qamar , Sibt ul Hassan , Pengkun Xia , Lei Ma , Xiaohui Gao , Lianwen Deng","doi":"10.1016/j.orgel.2025.107197","DOIUrl":"10.1016/j.orgel.2025.107197","url":null,"abstract":"<div><div>In this work, a series of nitrogen and sulfur co-doped carbon dots (CDs) were synthesized with high photoluminescence quantum yields (PLQYs) and outstanding thermal stability. With the reaction solvent changing from water, ethanol, methanol, and dimethylformamide (DMF), a significant fluorescence emission with PLQY improvement from 42 %, 33 %, 25 %, and 18 %, respectively, accompanied by a red shift from 430 to 590 nm, (the color changes from blue, green, yellow, and red respectively). Simultaneously, excellent fluorescence stability can also be obtained across temperatures ranging from 15 to 95 °C. Combined with the density functional calculations (DFT) results, the underlying mechanism investigation reveals that the color change of fluorescence emission was probably induced by the increased particle size of CDs and increased graphitic N content. The enhanced thermal stability is induced by the presence of stable surface functional groups, including C=O, C=N, C=S, and -NH, among others, contributing to improved hydrophilicity, regulated particle aggregation, and mitigated thermal oxidation by limiting oxygen diffusion to fluorescent hubs. Notably, the obtained outstanding optical properties finally render these multicolor CDs suitable for information encryption and anti-counterfeiting applications.</div></div>","PeriodicalId":399,"journal":{"name":"Organic Electronics","volume":"139 ","pages":"Article 107197"},"PeriodicalIF":2.7,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143395348","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-16DOI: 10.1016/j.orgel.2025.107198
Fang Wan , Nan Wu , Xinxin Peng , Xiaoxue Ren , Yongbo Yuan , Yun Lin
All-inorganic perovskites CsPbI2Br have gained much research interest in photovoltaics due to their excellent thermal stability. However, all-inorganic perovskite solar cells (PSCs) are prone to form defective perovskite films, which are detrimental to their high power conversion efficiencies (PCEs). In this study, CsPbI2Br PSCs with improved PCEs have been developed by introducing 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4) and tris(2-aminoethyl)amine (TAEA) as co-passivators. It is shown that BMIMBF4 additive improves the quality of perovskite films with reduced defect density, enhanced device efficiency, and increased phase stability in ambient atmosphere. By using TAEA as a co-passivator, the non-radiative recombination of PSCs is further suppressed, which cannot be achieved by BMIMBF4 alone. Moreover, after treating the perovskite surface with TAEA, the activation energy for ion migration is increased. The decelerated ion migration in CsPbI2Br solar cells leads to the illusion of a larger hysteresis effect but results in a higher steady-state output efficiency. The steady-state PCE of the optimized CsPbI2Br solar cells increased from 7.2 % to 11.3 %.
{"title":"Effect of Co-passivation on CsPbI2Br perovskite solar cells with increased photovoltaic efficiency","authors":"Fang Wan , Nan Wu , Xinxin Peng , Xiaoxue Ren , Yongbo Yuan , Yun Lin","doi":"10.1016/j.orgel.2025.107198","DOIUrl":"10.1016/j.orgel.2025.107198","url":null,"abstract":"<div><div>All-inorganic perovskites CsPbI<sub>2</sub>Br have gained much research interest in photovoltaics due to their excellent thermal stability. However, all-inorganic perovskite solar cells (PSCs) are prone to form defective perovskite films, which are detrimental to their high power conversion efficiencies (PCEs). In this study, CsPbI<sub>2</sub>Br PSCs with improved PCEs have been developed by introducing 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF<sub>4</sub>) and tris(2-aminoethyl)amine (TAEA) as co-passivators. It is shown that BMIMBF<sub>4</sub> additive improves the quality of perovskite films with reduced defect density, enhanced device efficiency, and increased phase stability in ambient atmosphere. By using TAEA as a co-passivator, the non-radiative recombination of PSCs is further suppressed, which cannot be achieved by BMIMBF<sub>4</sub> alone. Moreover, after treating the perovskite surface with TAEA, the activation energy for ion migration is increased. The decelerated ion migration in CsPbI<sub>2</sub>Br solar cells leads to the illusion of a larger hysteresis effect but results in a higher steady-state output efficiency. The steady-state PCE of the optimized CsPbI<sub>2</sub>Br solar cells increased from 7.2 % to 11.3 %.</div></div>","PeriodicalId":399,"journal":{"name":"Organic Electronics","volume":"139 ","pages":"Article 107198"},"PeriodicalIF":2.7,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-16DOI: 10.1016/j.orgel.2025.107199
Li Zhu , Xiang Wan , Junchen Lin , Pengyu Chen , Zhongzhong Luo , Huabin Sun , Shancheng Yan , Chee Leong Tan , Zhihao Yu , Yong Xu
Reservoir Computing (RC) is an efficient framework for processing sequential data. It captures the dynamic features of complex data through high-dimensional mapping, significantly enhancing machine learning capability. However, due to the lack of suitable materials and device fabrication processes, developing highly energy-efficient, flexible, and wearable RC systems remains a challenging task. In this paper, flexible ion-gated transistors were fabricated by spin-coating process at room temperature, utilizing polyimide (PI) as the flexible substrate, polyvinyl alcohol (PVA) doped with lithium perchlorate (LiClO4) as the gate dielectric, and poly[(bithiophene)-alternate-(2,5-di(2-octyldodecyl)-3,6-di(thienyl)-pyrrolyl pyrrolidone)] (DPPT-TT) as the organic semiconductor. Based on the electric double-layer (EDL) coupling in ion-gated transistors and the rich ionic dynamics, the device can simulate nonlinear synaptic functions such as excitatory postsynaptic current (EPSC), multi-pulse facilitation, and learning-forgetting-relearning behaviors. Based on the transistors’ nonlinear synaptic functions, the constructed RC system can enhance image features while reducing the image size by half, effectively extracting and amplifying hidden features in the original images. In the handwritten digit recognition task, the RC system improved the recognition rate from 79.8 % to 90.6 %, compared to an Artificial Neural Network (ANN) of the same scale. The effective combination of flexible organic ion-gated transistors and the RC framework will undoubtedly contribute to the further development of the next generation of wearable intelligent systems.
{"title":"Reservoir computing for image processing based on ion-gated flexible organic transistors with nonlinear synaptic dynamics","authors":"Li Zhu , Xiang Wan , Junchen Lin , Pengyu Chen , Zhongzhong Luo , Huabin Sun , Shancheng Yan , Chee Leong Tan , Zhihao Yu , Yong Xu","doi":"10.1016/j.orgel.2025.107199","DOIUrl":"10.1016/j.orgel.2025.107199","url":null,"abstract":"<div><div>Reservoir Computing (RC) is an efficient framework for processing sequential data. It captures the dynamic features of complex data through high-dimensional mapping, significantly enhancing machine learning capability. However, due to the lack of suitable materials and device fabrication processes, developing highly energy-efficient, flexible, and wearable RC systems remains a challenging task. In this paper, flexible ion-gated transistors were fabricated by spin-coating process at room temperature, utilizing polyimide (PI) as the flexible substrate, polyvinyl alcohol (PVA) doped with lithium perchlorate (LiClO<sub>4</sub>) as the gate dielectric, and poly[(bithiophene)-alternate-(2,5-di(2-octyldodecyl)-3,6-di(thienyl)-pyrrolyl pyrrolidone)] (DPPT-TT) as the organic semiconductor. Based on the electric double-layer (EDL) coupling in ion-gated transistors and the rich ionic dynamics, the device can simulate nonlinear synaptic functions such as excitatory postsynaptic current (EPSC), multi-pulse facilitation, and learning-forgetting-relearning behaviors. Based on the transistors’ nonlinear synaptic functions, the constructed RC system can enhance image features while reducing the image size by half, effectively extracting and amplifying hidden features in the original images. In the handwritten digit recognition task, the RC system improved the recognition rate from 79.8 % to 90.6 %, compared to an Artificial Neural Network (ANN) of the same scale. The effective combination of flexible organic ion-gated transistors and the RC framework will undoubtedly contribute to the further development of the next generation of wearable intelligent systems.</div></div>","PeriodicalId":399,"journal":{"name":"Organic Electronics","volume":"139 ","pages":"Article 107199"},"PeriodicalIF":2.7,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140407","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-13DOI: 10.1016/j.orgel.2025.107196
Zi-Qi Chen , Han Liu , Xiao-Jing Wang , Jian Fan , Yue-Min Xie , Man-Keung Fung
White organic light-emitting diode (WOLED) has been recognized as a healthy light source. However, the device performance is still limited by the hosts or emitters. Herein, multiple-exciplex hosts are developed for WOLEDs, in which a novel exciplex host consisting of a thermally activated delayed fluorescent material, triazine–carbazole (Trz-PhCz), and an electron-transport material, 4,6-bis[3,5-(dipyrid-4-yl)phenyl]-2-methylpyrimidine (B4PyMPM), is adopted for green, yellow, orange and red phosphorescent dopants, of which high external quantum efficiencies (EQEs) of 25.0 %, 30.7 %, 32.5 % and 26.2 %, respectively, are achieved. On the other hand, a high-energy exciplex host consisting of 9,9′-biphenyl-3,3′-diylbis-9H-carbazole (mCBP) and B4PyMPM is designed for the blue emitter, iridium(III)bis(4,6-(difluorophenyl)-pyridinato-N,C2’) picolinate (FIrpic), which guarantees a maximum EQE of 26.3 %. The small exciton energy difference between the mCBP:B4PyMPM and Trz-PhCz:B4PyMPM hosts can facilitate efficient energy transfer between the hosts. As a result, these exciplex hosts facilitate energy-efficient WOLEDs with a maximum EQE, power efficiency and current efficiency of 36.9 %, 137.4 lm W−1 and 106.7 cd A−1, respectively, without using any optical out-coupling techniques, which provides inspiration for the future design of efficient OLEDs.
{"title":"Ultra-high-efficiency white organic light-emitting diodes based on TADF material incorporated efficient exciplex hosts","authors":"Zi-Qi Chen , Han Liu , Xiao-Jing Wang , Jian Fan , Yue-Min Xie , Man-Keung Fung","doi":"10.1016/j.orgel.2025.107196","DOIUrl":"10.1016/j.orgel.2025.107196","url":null,"abstract":"<div><div>White organic light-emitting diode (WOLED) has been recognized as a healthy light source. However, the device performance is still limited by the hosts or emitters. Herein, multiple-exciplex hosts are developed for WOLEDs, in which a novel exciplex host consisting of a thermally activated delayed fluorescent material, triazine–carbazole (Trz-PhCz), and an electron-transport material, 4,6-bis[3,5-(dipyrid-4-yl)phenyl]-2-methylpyrimidine (B4PyMPM), is adopted for green, yellow, orange and red phosphorescent dopants, of which high external quantum efficiencies (EQEs) of 25.0 %, 30.7 %, 32.5 % and 26.2 %, respectively, are achieved. On the other hand, a high-energy exciplex host consisting of 9,9′-biphenyl-3,3′-diylbis-9H-carbazole (mCBP) and B4PyMPM is designed for the blue emitter, iridium(III)bis(4,6-(difluorophenyl)-pyridinato-N,C2’) picolinate (FIrpic), which guarantees a maximum EQE of 26.3 %. The small exciton energy difference between the mCBP:B4PyMPM and Trz-PhCz:B4PyMPM hosts can facilitate efficient energy transfer between the hosts. As a result, these exciplex hosts facilitate energy-efficient WOLEDs with a maximum EQE, power efficiency and current efficiency of 36.9 %, 137.4 lm W<sup>−1</sup> and 106.7 cd A<sup>−1</sup>, respectively, without using any optical out-coupling techniques, which provides inspiration for the future design of efficient OLEDs.</div></div>","PeriodicalId":399,"journal":{"name":"Organic Electronics","volume":"139 ","pages":"Article 107196"},"PeriodicalIF":2.7,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140500","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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