Organic Electronics最新文献

The 5,10,15-trihexyl-10,15-dihydro-5H-diindolo[3,2-a:3′,2′-c]carbazole core, namely triindole, is well-known for its prominent hole-transporting properties and air stability. The functionalization of this core is also rather versatile, which allows the modulation of its properties by anchoring targeted scaffolds to different positions, e.g. 3,8,13 (para with respect to the nitrogens), 2,7,12 (analogously meta) or the nitrogen heteroatoms. Therefore, triindole excels as a pivotal semiconductor to be exploited in long-lasting organic thin-film transistors (OTFTs). This report aims to shed light on the effect of functionalizing whether para or meta positions with sulfurated moieties, in the pursuit of an enhanced performance in OTFTs. Remarkably, meta-substituted derivatives outshone their para- counterparts in terms of thermal, optical, intermolecular arrangement and semiconductor properties, claiming mobility values up to 2 × 10⁻³ cm² V⁻¹ s⁻¹ and a shelf lifetime beyond the analyzed period of 5 months. Analysis of the thin films by grazing incidence X-ray diffraction (GIRXD) and atomic force microscopy (AFM) revealed that the meta-substitution also induces a higher degree of order and better morphology, further corroborating the potential of this structural approach.

Fused-ring compounds containing a N–B–N (NBN) unit have emerged as a class of emitters for organic light-emitting diodes (OLEDs) in recent years. However, despite the success of these compounds in achieving efficient green OLEDs, their application in blue OLEDs has not yet been realized. In this study, two new NBN-containing compounds featuring unsymmetrical molecular structures are designed and synthesized. The structural design endows the compounds with efficient blue emission and narrower emission bandwidths. A blue fluorescent OLED based on one of the compounds exhibits simultaneously a high external quantum efficiency of 4.2% and an excellent Commission Internationale de L'Eclairage (CIE) coordinate of (0.152, 0.096). The impressive performance of the OLED device suggests that with proper molecular designs, NBN-containing compounds possess great potential as excellent blue emitters for OLEDs, and thus merit further investigation and attention.

In order to address the question of high cost and poverty corrosion resistance of platinum electrodes used in dye-sensitized solar cells (DSSCs). In this experiment, sodium lignosulfonate (SL) was used as a precursor to prepare oxygen-nitrogen-sulfur (ONS) co-doped lignin hierarchical porous carbon through pre-carbonization and KOH chemical activation. It exhibits 2252.145 m²g^-1 of BET-specific surface area, 1.613 cm³g^-1 of total pore volume, and a profusion of micro, meso, and macropores. The total ONS doping in lignin hierarchical porous carbon is 9.47 %–14.99 %. When used as the counter electrode (CE) in a DSSC assembly, lignin hierarchical porous carbon doped with ONS achieved a power conversion efficiency (PCE) of 8.89 %, which is 9 % higher than the platinum electrode's (8.14 %) value. This highlights the potential application of hierarchical porous carbon derived from sodium lignosulfonate in more cost-effective DSSCs.

Electrochromic (EC) devices based on conjugated polymers (CPs) with optical activity was developed. Asymmetric EC polymers are synthesised through electrochemical polymerisation in cholesteric liquid crystals (CLCs). This asymmetric polymerisation method transcribes the helical structure of CLCs to CPs. The EC performance of chiral EC polymers remains insufficiently explored. This study elucidated the impact of the electronic and structural properties of chiral EC polymers on their EC performances, focusing on optical contrast, response time, and cycle stability. Compared with 3,4-(ethylenedithia)thiophene (EDTT) units with an electron-withdrawing group, 3,4-(ethylenedioxy)thiophene (EDOT) units with an electron-donating group exhibited a stable oxidation state, enhanced cycle stability, and accelerated response time. Moreover, 3,4-(propylenedioxy)thiophene adorned with bulky methyl groups (dMProDOT) had a higher EC performance, characterised by a bleaching/colouring time of 1.1 s and high cycle stability. The EC performance of these asymmetric EC polymers was significantly influenced by the structural and electrical properties of the constituent units. The findings of this study provide valuable molecular design guidelines for the application and optimisation of the asymmetric EC polymers.

This review elucidates the potential of Organic Thin Film Transistors (OTFTs) for biocompatible synaptic devices in in-vivo medical applications. Emphasizing attributes like flexibility and reduced environmental footprint, OTFTs are distinguished from traditional silicon counterparts. The synthesis of electronic capabilities and biological emulation in synaptic transistors is dissected, spotlighting their role in neuromorphic computing. This exploration centers on biocompatibility, detailing criteria, challenges, and the integration of organic electronics with living systems. Furthermore, potential applications, innovations, and future prospects of OTFT-driven synaptic devices are addressed. Critical technical, ethical, and societal challenges within this interdisciplinary nexus are outlined. The confluence of OTFTs, synaptic transistors, and biocompatibility heralds a paradigm shift in techno-biological convergence.

In organic solar cells, the absorption range and extinction coefficient of the active layer not only affect the charge separation and carrier transfer efficiency of excitons, but also influence the J_SC, and thus the device efficiency. Herein, an efficient nonfullerene polymer solar cells (NF–PSCs) based on a medium-bandgap (MBG) polymer donor PBDTTS-TClQx comprising chlorinethiophene quinoxaline (Qx) unit and a small molecule nonfullerene acceptor (SM-NFA) Y6 is developed. The PBDTTS-TClQx shows a strong absorption in the wavelength region of 330∼750 nm with an optical band gaps (E_g^opt) of 1.68 eV, which is well complementary with that of Y6 (1.33 eV) and facilitates achieving of high short-circuit current (J_SC) in PSCs. As a result, the PBDTTS-TClQx:Y6-based PSCs achieved a power conversion efficiency (PCE) of 14.28% with a J_SC of 25.9 mA cm⁻². The J_SC of 25.9 mA cm⁻² achieved is among the highest reported for Qx-based polymer donors in PSCs.

The reflection losses are among the principal causes that limiting the performances of the solar cells. Indeed, the conventional organic solar cell (OSC) provides a relatively low photocurrent mainly due to light reflection at the front and back sides of the glass-substrate. To overcome this limitation we propose an optimized hybrid antireflective structure. The proposed design is a combination between multilayer antireflection coating (MARC) and moth eye structure (MES). The OSC with this antireflection coating, consisting of thin coherent multilayer stack and moth eye subwavelength structure, is modeled using transfer matrix method (TMM) and effective medium theory (EMT). In this work, several antireflection coating designs with different dielectric material films are investigated. The layer thicknesses of the MARC were tuned such that they obey to quarter-quarter-quarter (Q-Q-Q) and quarter-half-quarter (Q-H-Q) wavelength rules to obtain zero reflectance. Based on these configurations, we performed an optimization algorithm to design the antireflection coating that maximizes the short circuit photocurrent density (J_SC). The optical analysis is applied to ITO/PEDOT:PSS/P3HT:PCBM/Al bulk heterojunction (BHJ) organic solar cell. The highest value of short circuit photocurrent density is obtained for OSC with hybrid MES/Glass-substrate/MARC(QHQ) antireflective structure using Al₂O₃/ZrO₂/M-optm material films. In comparison with the conventional organic solar cell without antireflection coating, the short circuit photocurrent density was improved by 5% at normal incidence. Besides, the antireflection effect is maintained even at large incidence angle of 68° thanks to the omnidirectional optical propriety of the moth eye structure.

A very promising approach to achieving stable polymer P-N junctions is polymer light-emitting electrochemical cells (LECs). In LECs, under a specific voltage bias, the injection of carriers into the polymer occurs through a redox reaction and subsequently gets compensated by opposite ions, resulting in the creation of electrochemical doping. Unlike organic light-emitting diodes, which have numerous mature electrical current models serving as invaluable tools for understanding the underlying mechanism and predicting device performance, LECs lack such modeling. This lack of modeling stems from the greater complexity of LECs, as the electrical current in LECs is composed of not only electronic components but also ionic contributions, along with a side-reaction portion arising from the electrochemical reaction. This work demonstrates an electrical current model for LECs, which is simple and accurate enough for practical applications. The model achieves a quantitative separation of electronic and ionic charge contributions to the electrical currents, as well as provides insights into the distribution of oxygen through operation schemes. Additionally, this paper incorporates the relationships between oxygen level, voltage, temperature, and current into the current model, thereby discerningly formulating expressions for ionic and electronic currents within the model. This demonstrates a precise equation for LEC electric current.

Pseudo-halide substitution is an effective approach to enhance the performance and stability of perovskite optoelectronic devices. However, the role of pseudo-halide ions played in the perovskite light-emitting diodes (PeLEDs) is still rarely investigated. Herein, we have synthesized the organic salt PEABF₄ (PEA = phenylethylamine) as a pseudo halide substitute for surface halides in PEABr and fabricate quasi two-dimensional (quasi-2D) PeLEDs. The incorporation of BF₄⁻ anion improves the photoluminescence (PL) intensity and lifetime by taking advantage of improved crystallinity and enlarged grain size. The BF₄⁻ substituted PeLEDs shows great improvement of performance to the control devices. The optimized device with structure of indium tin oxide-coated glass (ITO(glass))/poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate)(PEDOT:PSS)/perovskite/4,7-Diphenyl-1,10-phenanthroline (Bphen)/Ag produces a maximum luminance at 44850 cd/m², and an efficiency of 11.5 cd/A, respectively. Through further investigation by optical and electrical characterization, we find the substitution of BF₄⁻ anion has merits on the enhancement of exciton binding energy and suppression of non-radiative trap-assisted recombination on the surface. These results provide better understanding of pseudo-halide's benefits in perovskite light-emitting devices.

Functional and low-cost switching materials are necessary to sustain the development of data storage and brain-inspired computing technologies. Polypyrrole (PPy) is one of the potential organic polymer materials for resistive switching (RS) applications. Given this, the present work reports the electrochemical synthesis of PPy and gold (Au) decorated PPy (Au-PPy) switching layers for non-volatile memory and neuromorphic computing applications. Among two switching layer materials, the Au decorated PPy (Ag/Au-PPy/Pt) shows good bipolar RS properties in terms of cyclic stability (16,000 cycles), memory retention (6000 s), and memory window (>60). Moreover, Ag/Au-PPy/Pt device realistically mimic the various bio-synaptic properties such as potentiation, depression, excitatory post-synaptic current (EPSC), and paired-pulse facilitation (PPF) index (%) as compared to Ag/PPy/Pt device. The double-valued charge-flux relation asserted that both devices are non-ideal memristors. Various statistical techniques such as cumulative probability, Weibull distribution, and time series analysis techniques were utilized to understand, model, and predict the switching variation of both devices. Moreover, the cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques were probed to understand the RS process of the devices. The conduction and plausible RS mechanisms of the optimized device were also reported. The results of the present work assert that the Au-decorated PPy is a potential organic polymer material for data storage and neuromorphic computing applications.