Pub Date : 2010-06-20DOI: 10.1109/PVSC.2010.5614155
C. Fella, S. Buecheler, D. Guettler, J. Perrenoud, A. Uhl, A. Tiwari
Zinc sulfide (ZnS) buffer layer deposited by an ultrasonic spray pyrolysis (USP) method is a feasible alternative to the chemical bath deposited cadmium sulfide (CdS) buffer layer. In the present work we report the results of a low-cost, non-vacuum and in-line compatible method to grow ZnS thin films. We investigated the properties of USP-ZnS films grown at different substrate temperatures and spray solution precursors. Rutherford backscattering spectrometry measurements were done for quantitative chemical composition information, revealing chlorine impurities depending on the deposition temperature as well as on the chemical precursors. By optimizing the spray parameters of USP-ZnS buffer layers on Cu(In,Ga)(S,Se)2 absorbers, a maximum solar cell efficiency of 10.8% after air-annealing was achieved, whilst the CdS reference fabricated on a similar absorber reached 11.4%. A significant increase of the short circuit current is observed as compared to the CdS reference due to a gain in the blue wavelength region.
{"title":"Ultrasonically sprayed Zinc sulfide buffer layers for Cu(In,Ga)(S,Se)2 solar cells","authors":"C. Fella, S. Buecheler, D. Guettler, J. Perrenoud, A. Uhl, A. Tiwari","doi":"10.1109/PVSC.2010.5614155","DOIUrl":"https://doi.org/10.1109/PVSC.2010.5614155","url":null,"abstract":"Zinc sulfide (ZnS) buffer layer deposited by an ultrasonic spray pyrolysis (USP) method is a feasible alternative to the chemical bath deposited cadmium sulfide (CdS) buffer layer. In the present work we report the results of a low-cost, non-vacuum and in-line compatible method to grow ZnS thin films. We investigated the properties of USP-ZnS films grown at different substrate temperatures and spray solution precursors. Rutherford backscattering spectrometry measurements were done for quantitative chemical composition information, revealing chlorine impurities depending on the deposition temperature as well as on the chemical precursors. By optimizing the spray parameters of USP-ZnS buffer layers on Cu(In,Ga)(S,Se)2 absorbers, a maximum solar cell efficiency of 10.8% after air-annealing was achieved, whilst the CdS reference fabricated on a similar absorber reached 11.4%. A significant increase of the short circuit current is observed as compared to the CdS reference due to a gain in the blue wavelength region.","PeriodicalId":6424,"journal":{"name":"2010 35th IEEE Photovoltaic Specialists Conference","volume":"1 1","pages":"003394-003397"},"PeriodicalIF":0.0,"publicationDate":"2010-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82328825","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-06-20DOI: 10.1109/PVSC.2010.5614624
J. Kim, Y. Shin, B. Ahn
Polycrystalline Cux(In,Ga)ySez films were deposited on Mo coated soda-lime glass substrate by three-stage co-evaporation process. Cu content x can be controlled by deposition times of each stage. The presence of β-Cu(In,Ga)3Se5 phase in films was confirmed by X-ray Diffraction and Auger Electron Spectroscopy when the x decreased below 0.5. The grain size became smaller as the x decreased. The absorption edge moved to shorter wavelength and the optical transmittance of long wavelength noticeably increased in β-Cu(In,Ga)3Se5 system comparing the conventional Cu(In,Ga)Se2. Its optical band gap was 1.49eV. The CdS/Cu(In0.3Ga0.7)3Se5 solar cell showed the efficiency of 8.09% with an active area of 0.44cm2. High transmittance and band gap are desirable to be a light absorber for top cell, but further effort is necessary to improve cell efficiency for the top cell application in CIGS tandem solar cells.
{"title":"Preparation of β-Cu (In,Ga)3Se5 thin films for wide band gap absorber for top cell in CIGS tandem structure","authors":"J. Kim, Y. Shin, B. Ahn","doi":"10.1109/PVSC.2010.5614624","DOIUrl":"https://doi.org/10.1109/PVSC.2010.5614624","url":null,"abstract":"Polycrystalline Cu<inf>x</inf>(In,Ga)<inf>y</inf>Se<inf>z</inf> films were deposited on Mo coated soda-lime glass substrate by three-stage co-evaporation process. Cu content x can be controlled by deposition times of each stage. The presence of β-Cu(In,Ga)<inf>3</inf>Se<inf>5</inf> phase in films was confirmed by X-ray Diffraction and Auger Electron Spectroscopy when the x decreased below 0.5. The grain size became smaller as the x decreased. The absorption edge moved to shorter wavelength and the optical transmittance of long wavelength noticeably increased in β-Cu(In,Ga)<inf>3</inf>Se<inf>5</inf> system comparing the conventional Cu(In,Ga)Se<inf>2</inf>. Its optical band gap was 1.49eV. The CdS/Cu(In<inf>0.3</inf>Ga<inf>0.7</inf>)<inf>3</inf>Se<inf>5</inf> solar cell showed the efficiency of 8.09% with an active area of 0.44cm<sup>2</sup>. High transmittance and band gap are desirable to be a light absorber for top cell, but further effort is necessary to improve cell efficiency for the top cell application in CIGS tandem solar cells.","PeriodicalId":6424,"journal":{"name":"2010 35th IEEE Photovoltaic Specialists Conference","volume":"144 1","pages":"003439-003442"},"PeriodicalIF":0.0,"publicationDate":"2010-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78680040","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-06-20DOI: 10.1109/PVSC.2010.5614048
S. Mack, U. Jager, Gero Kastner, E. A. Wotke, U. Belledin, A. Wolf, R. Preu, D. Biro
Higher solar cell efficiencies enable a reduction of the cost per watt ratio, if production effort is maintained at an acceptable level. A proven high-efficiency concept is the passivated emitter and rear cell (PERC) [1]. However, the transfer of this solar cell structure from demonstrator level to industrial application is challenging. We present a simple approach for the industrial fabrication of PERC solar cells which utilizes the simultaneous passivation of the front emitter and the rear surface by a thin layer of thermally grown oxide. This Thermal Oxide Passivated All Sides (TOPAS) structure represents an industrially feasible implementation of the PERC concept.
{"title":"Towards 19% efficient industrial PERC devices using simultaneous front emitter and rear surface passivation by thermal oxidation","authors":"S. Mack, U. Jager, Gero Kastner, E. A. Wotke, U. Belledin, A. Wolf, R. Preu, D. Biro","doi":"10.1109/PVSC.2010.5614048","DOIUrl":"https://doi.org/10.1109/PVSC.2010.5614048","url":null,"abstract":"Higher solar cell efficiencies enable a reduction of the cost per watt ratio, if production effort is maintained at an acceptable level. A proven high-efficiency concept is the passivated emitter and rear cell (PERC) [1]. However, the transfer of this solar cell structure from demonstrator level to industrial application is challenging. We present a simple approach for the industrial fabrication of PERC solar cells which utilizes the simultaneous passivation of the front emitter and the rear surface by a thin layer of thermally grown oxide. This Thermal Oxide Passivated All Sides (TOPAS) structure represents an industrially feasible implementation of the PERC concept.","PeriodicalId":6424,"journal":{"name":"2010 35th IEEE Photovoltaic Specialists Conference","volume":"46 1","pages":"000034-000038"},"PeriodicalIF":0.0,"publicationDate":"2010-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87007906","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-06-20DOI: 10.1109/PVSC.2010.5614432
Y. Matsumoto, M. Ortega, V. Sanchez, F. Wunsch, J. Urbano
P-type-microcrystalline-silicon / n-type-crystalline-silicon hetero-junction solar cell has been prepared by means of hot-wire chemical vapor deposition (HW-CVD) technique. The solar cell structure was illuminated on the opposite side of the normally-formed heterojunction. With this inverted structure, the photovoltaic cell has the design potential to improve the light-incident surface-texturing with the possibility to avoid the use of transparent conducting oxide (TCO). Solar cells were fabricated on Czochralsky (CZ)-grown phosphorous-doped crystalline-silicon (c-Si) substrates within 0.5 to 1 ohm-cm. HW-CVD has employed for the deposition of a very thin intrinsic hydrogenated amorphous silicon (i-a-Si) as a buffer-layer as a heterojunction interface, and boron-doped hydrogenated microcrystalline silicon (p-μc-Si) on c-Si substrate. The tungsten catalyst temperature (Tfil) was settled to 1600 °C and 1950 °C for i-a-Si and p-μc-Si films, respectively. Silane (SiH4), hydrogen (H2) and diluted diborane (B2H6) gases were used for p-μc-Si at the substrate temperatures (Tsub) of 200 °C. The obtained I–V characteristics under simulated solar radiation at 100mW/cm2 are: Jsc =26.1 mA/cm2; Voc = 545 mV; Jm = 21.4 mA/cm2; Vm = 410 mV; FF = 61.7%, with total area efficiency of η= 8.8%. The solar cell has great potential to improve its conversion efficiency with proper surface passivation and antireflection coat.
{"title":"HW-CVD deposited μc-Si:H for the inverted heterojunction solar cell","authors":"Y. Matsumoto, M. Ortega, V. Sanchez, F. Wunsch, J. Urbano","doi":"10.1109/PVSC.2010.5614432","DOIUrl":"https://doi.org/10.1109/PVSC.2010.5614432","url":null,"abstract":"P-type-microcrystalline-silicon / n-type-crystalline-silicon hetero-junction solar cell has been prepared by means of hot-wire chemical vapor deposition (HW-CVD) technique. The solar cell structure was illuminated on the opposite side of the normally-formed heterojunction. With this inverted structure, the photovoltaic cell has the design potential to improve the light-incident surface-texturing with the possibility to avoid the use of transparent conducting oxide (TCO). Solar cells were fabricated on Czochralsky (CZ)-grown phosphorous-doped crystalline-silicon (c-Si) substrates within 0.5 to 1 ohm-cm. HW-CVD has employed for the deposition of a very thin intrinsic hydrogenated amorphous silicon (i-a-Si) as a buffer-layer as a heterojunction interface, and boron-doped hydrogenated microcrystalline silicon (p-μc-Si) on c-Si substrate. The tungsten catalyst temperature (Tfil) was settled to 1600 °C and 1950 °C for i-a-Si and p-μc-Si films, respectively. Silane (SiH4), hydrogen (H2) and diluted diborane (B2H6) gases were used for p-μc-Si at the substrate temperatures (Tsub) of 200 °C. The obtained I–V characteristics under simulated solar radiation at 100mW/cm2 are: Jsc =26.1 mA/cm2; Voc = 545 mV; Jm = 21.4 mA/cm2; Vm = 410 mV; FF = 61.7%, with total area efficiency of η= 8.8%. The solar cell has great potential to improve its conversion efficiency with proper surface passivation and antireflection coat.","PeriodicalId":6424,"journal":{"name":"2010 35th IEEE Photovoltaic Specialists Conference","volume":"72 1","pages":"001450-001455"},"PeriodicalIF":0.0,"publicationDate":"2010-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88226656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-06-20DOI: 10.1109/PVSC.2010.5617021
R. Ruther, L. Nascimento, J. Urbanetz Junior, P. Pfitscher, T. Viana
In this paper we present the performance assessment of the first grid-connected, building-integrated, thin-film PV system installed in Brazil in 1997. In the 12-years period since start up, the 40m2, 2kWp double-junction amorphous silicon BIPV generator operated continuously, with minimum downtime and high performance ratios. We also discuss reliability issues related to system design and inverter performance and replacement for the continuous operation of this distributed energy source in the urban environment of a warm-climate metropolitan state capital in Brazil.
{"title":"Long-term performance of the first grid-connected, building-integrated amorphous silicon PV installation in Brazil","authors":"R. Ruther, L. Nascimento, J. Urbanetz Junior, P. Pfitscher, T. Viana","doi":"10.1109/PVSC.2010.5617021","DOIUrl":"https://doi.org/10.1109/PVSC.2010.5617021","url":null,"abstract":"In this paper we present the performance assessment of the first grid-connected, building-integrated, thin-film PV system installed in Brazil in 1997. In the 12-years period since start up, the 40m2, 2kWp double-junction amorphous silicon BIPV generator operated continuously, with minimum downtime and high performance ratios. We also discuss reliability issues related to system design and inverter performance and replacement for the continuous operation of this distributed energy source in the urban environment of a warm-climate metropolitan state capital in Brazil.","PeriodicalId":6424,"journal":{"name":"2010 35th IEEE Photovoltaic Specialists Conference","volume":"154 1","pages":"002283-002286"},"PeriodicalIF":0.0,"publicationDate":"2010-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86214619","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-06-20DOI: 10.1109/PVSC.2010.5614640
C. Reichel, M. Reusch, F. Granek, M. Hermle, S. W.
Back-contacted back-junction silicon solar cells with a large emitter coverage (point-like base contacts) and a small emitter coverage (point-like emitter and base contacts) have been fabricated and analyzed. These solar cells feature an insulating thin film on the rear side in order to decouple the charge carrier collection geometry and the geometry of the metallization. It has been found, that for the investigated solar cells an increased collection efficiency is observed due to a significant reduction of electrical shading losses. Thus, high short-circuit currents could be achieved for both solar cell structures. Different insulating thin films, such as ALD Al2O3 and PECVD SiOx have been investigated. It has been found that ALD layers are already insulating for a thinner film thickness. By applying these insulating thin films to the investigated solar cell structures no significant shunts are introduced. For solar cells on 1 Ωcm n-type material and with a large emitter coverage an efficiency of 21.9% (Voc = 673 mV, Jsc = 40.6 mA/cm2, FF = 80.1%) could be obtained and for solar cells with a small emitter coverage an efficiency of 22.7% (Voc = 706 mV, Jsc = 41.0 mA/cm2, FF = 78.5%) has been achieved.
{"title":"Decoupling charge carrier collection and metallization geometry of back-contacted back-junction silicon solar cells by using insulating thin films","authors":"C. Reichel, M. Reusch, F. Granek, M. Hermle, S. W.","doi":"10.1109/PVSC.2010.5614640","DOIUrl":"https://doi.org/10.1109/PVSC.2010.5614640","url":null,"abstract":"Back-contacted back-junction silicon solar cells with a large emitter coverage (point-like base contacts) and a small emitter coverage (point-like emitter and base contacts) have been fabricated and analyzed. These solar cells feature an insulating thin film on the rear side in order to decouple the charge carrier collection geometry and the geometry of the metallization. It has been found, that for the investigated solar cells an increased collection efficiency is observed due to a significant reduction of electrical shading losses. Thus, high short-circuit currents could be achieved for both solar cell structures. Different insulating thin films, such as ALD Al2O3 and PECVD SiOx have been investigated. It has been found that ALD layers are already insulating for a thinner film thickness. By applying these insulating thin films to the investigated solar cell structures no significant shunts are introduced. For solar cells on 1 Ωcm n-type material and with a large emitter coverage an efficiency of 21.9% (Voc = 673 mV, Jsc = 40.6 mA/cm2, FF = 80.1%) could be obtained and for solar cells with a small emitter coverage an efficiency of 22.7% (Voc = 706 mV, Jsc = 41.0 mA/cm2, FF = 78.5%) has been achieved.","PeriodicalId":6424,"journal":{"name":"2010 35th IEEE Photovoltaic Specialists Conference","volume":"41 1","pages":"001034-001038"},"PeriodicalIF":0.0,"publicationDate":"2010-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83875792","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-06-20DOI: 10.1109/PVSC.2010.5616793
D. Datta, S. Sundar Kumar Iyer, Satyendra Kumar
The role of exciton blocking layer (EBL) in organic solar cells have been under intense investigation in the recent past. Although BCP (bathocuproine) has been commonly used as an EBL in CuPc/C60 based devices, its role as an effective optical spacer to increase the optical electric field intensity at the active layers, needs further investigation. In this work, using numerical techniques, we study the role of BCP as an optical spacer in CuPc/C60 based devices. For comparison, a higher refractive index material (TiOx; titanium suboxide) was also used. The optical constants of the BCP layer was extracted using spectroscopic ellipsometry using Tauc-Lorentz model dielectric function. The maximum device photocurrent density (Jsc-max) was simulated using transfer matrix formalism and exciton diffusion dynamics. The results with BCP as an optical spacer indicate that although a high gain in photocurrent can be obtained for devices with low active layer thicknesses, the enhancement in photocurrent from an already optimized device can at best be from 93.7 A/m2 to 98.7 A/m2, corresponding to a gain of only 5.3 %. Using a higher refractive index material such as TiOx, the current density for an already optimized device can at best be enhanced from 93.7 A/m2 to 97.5 A/m2, a gain of only 4 %. Overall, our results reveal that although the EBL acts as an optical spacer, the improvement in device absorption due to the optical effect is limited for an already optimized device. This indicates that the well known improvement in device performance by incorporating the buffer layer should be primarily related to other properties such as exciton blocking, electron transport, and avoiding acceptor damage during cathode deposition.
激子阻断层(EBL)在有机太阳能电池中的作用近年来得到了广泛的研究。虽然BCP (bathocuproine)在CuPc/C60基器件中通常用作EBL，但其作为有效的光间隔剂以增加有源层的光电场强度的作用还需要进一步研究。在这项工作中，我们使用数值技术研究了BCP作为光学间隔剂在基于CuPc/C60的器件中的作用。相比之下，一种更高折射率的材料(TiOx;也使用了亚氧化钛。利用陶克-洛伦兹模型介电函数，利用椭圆偏振光谱法提取了BCP层的光学常数。利用传递矩阵形式和激子扩散动力学模拟了器件最大光电流密度(Jsc-max)。以BCP作为光学间隔层的结果表明，虽然低有源层厚度的器件可以获得高光电流增益，但已经优化的器件的光电流增益最多可以从93.7 a /m2增加到98.7 a /m2，对应的增益仅为5.3%。使用更高折射率的材料，如TiOx，已经优化的器件的电流密度最多可以从93.7 a /m2提高到97.5 a /m2，增益仅为4%。总体而言，我们的研究结果表明，尽管EBL作为光学间隔器，但由于光学效应而导致的器件吸收的改善对于已经优化的器件是有限的。这表明，众所周知，通过加入缓冲层，器件性能的改善应该主要与其他特性有关，如激子阻断、电子传输，以及在阴极沉积过程中避免受体损伤。
{"title":"Role of exciton blocking layers as optical spacer in CuPc/C60 based organic solar cells","authors":"D. Datta, S. Sundar Kumar Iyer, Satyendra Kumar","doi":"10.1109/PVSC.2010.5616793","DOIUrl":"https://doi.org/10.1109/PVSC.2010.5616793","url":null,"abstract":"The role of exciton blocking layer (EBL) in organic solar cells have been under intense investigation in the recent past. Although BCP (bathocuproine) has been commonly used as an EBL in CuPc/C60 based devices, its role as an effective optical spacer to increase the optical electric field intensity at the active layers, needs further investigation. In this work, using numerical techniques, we study the role of BCP as an optical spacer in CuPc/C60 based devices. For comparison, a higher refractive index material (TiOx; titanium suboxide) was also used. The optical constants of the BCP layer was extracted using spectroscopic ellipsometry using Tauc-Lorentz model dielectric function. The maximum device photocurrent density (Jsc-max) was simulated using transfer matrix formalism and exciton diffusion dynamics. The results with BCP as an optical spacer indicate that although a high gain in photocurrent can be obtained for devices with low active layer thicknesses, the enhancement in photocurrent from an already optimized device can at best be from 93.7 A/m2 to 98.7 A/m2, corresponding to a gain of only 5.3 %. Using a higher refractive index material such as TiOx, the current density for an already optimized device can at best be enhanced from 93.7 A/m2 to 97.5 A/m2, a gain of only 4 %. Overall, our results reveal that although the EBL acts as an optical spacer, the improvement in device absorption due to the optical effect is limited for an already optimized device. This indicates that the well known improvement in device performance by incorporating the buffer layer should be primarily related to other properties such as exciton blocking, electron transport, and avoiding acceptor damage during cathode deposition.","PeriodicalId":6424,"journal":{"name":"2010 35th IEEE Photovoltaic Specialists Conference","volume":"94 1","pages":"000508-000512"},"PeriodicalIF":0.0,"publicationDate":"2010-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83912071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-06-20DOI: 10.1109/PVSC.2010.5616755
B. Shu, U. Das, J. Appel, B. McCandless, S. Hegedus, R. Birkmire
In this work, we investigated two alternative approaches for the front surface passivation of interdigitated back contact silicon heterojunction (IBC-SHJ) solar cells: (1) with plasma enhanced chemical vapor deposited (PEVCD) a-Si-based stack structure consisting of a-Si:H/a-SiNx:H/a-SiC:H, and (2) with physical vapor deposited (PVD) zinc sulfide (ZnS) film. The processing temperatures for both the approaches are under 300°C. Effective surface recombination velocities (SRV) of < 6.2cm/s and < 35cm/s are obtained with stack structure and ZnS respectively on n-type float zone (FZ) crystalline silicon (c-Si) wafers. The anti-reflection (AR) properties of these two passivation approaches are studied and the optimization procedure of the stack structure was discussed and shown to improve the photo-generated current. The IBC-SHJ solar cells were fabricated using both the front surface passivation approaches and a 15% cell efficiency was achieved on 150µm thick FZ c-Si wafer without surface texturing and optical optimization.
{"title":"Alternative approaches for low temperature front surface passivation of interdigitated back contact silicon heterojunction solar cell","authors":"B. Shu, U. Das, J. Appel, B. McCandless, S. Hegedus, R. Birkmire","doi":"10.1109/PVSC.2010.5616755","DOIUrl":"https://doi.org/10.1109/PVSC.2010.5616755","url":null,"abstract":"In this work, we investigated two alternative approaches for the front surface passivation of interdigitated back contact silicon heterojunction (IBC-SHJ) solar cells: (1) with plasma enhanced chemical vapor deposited (PEVCD) a-Si-based stack structure consisting of a-Si:H/a-SiNx:H/a-SiC:H, and (2) with physical vapor deposited (PVD) zinc sulfide (ZnS) film. The processing temperatures for both the approaches are under 300°C. Effective surface recombination velocities (SRV) of < 6.2cm/s and < 35cm/s are obtained with stack structure and ZnS respectively on n-type float zone (FZ) crystalline silicon (c-Si) wafers. The anti-reflection (AR) properties of these two passivation approaches are studied and the optimization procedure of the stack structure was discussed and shown to improve the photo-generated current. The IBC-SHJ solar cells were fabricated using both the front surface passivation approaches and a 15% cell efficiency was achieved on 150µm thick FZ c-Si wafer without surface texturing and optical optimization.","PeriodicalId":6424,"journal":{"name":"2010 35th IEEE Photovoltaic Specialists Conference","volume":"47 1","pages":"003223-003228"},"PeriodicalIF":0.0,"publicationDate":"2010-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82855153","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-06-20DOI: 10.1109/PVSC.2010.5616788
J. Karp, E. Tremblay, J. Ford
We recently proposed a micro-optic solar concentrator using a two-dimensional array of small-aperture lenses focusing into a planar slab waveguide. By placing mirrors at each lens focus, light collected by the lens array reflects into a common slab waveguide at angles which guide by total internal reflection. Coupled sunlight propagates within the slab until reaching a photovoltaic cell mounted along the edge(s). Simulations of this geometry reveal designs with 89% and 81.9% optical efficiency at 100x and 300x geometric concentrations respectively. The micro-optic concentrator was previously fabricated as a proof-of-concept, but exhibited poor performance due to lens aberrations. Here, we present a 2nd-generation system using a better-suited lens array and achieve >52% measured efficiency. We also discuss performance tradeoffs associated with micro-optic concentration and explore secondary coupler designs as a means to increase both efficiency and concentration.
{"title":"Micro-optic solar concentration and next-generation prototypes","authors":"J. Karp, E. Tremblay, J. Ford","doi":"10.1109/PVSC.2010.5616788","DOIUrl":"https://doi.org/10.1109/PVSC.2010.5616788","url":null,"abstract":"We recently proposed a micro-optic solar concentrator using a two-dimensional array of small-aperture lenses focusing into a planar slab waveguide. By placing mirrors at each lens focus, light collected by the lens array reflects into a common slab waveguide at angles which guide by total internal reflection. Coupled sunlight propagates within the slab until reaching a photovoltaic cell mounted along the edge(s). Simulations of this geometry reveal designs with 89% and 81.9% optical efficiency at 100x and 300x geometric concentrations respectively. The micro-optic concentrator was previously fabricated as a proof-of-concept, but exhibited poor performance due to lens aberrations. Here, we present a 2nd-generation system using a better-suited lens array and achieve >52% measured efficiency. We also discuss performance tradeoffs associated with micro-optic concentration and explore secondary coupler designs as a means to increase both efficiency and concentration.","PeriodicalId":6424,"journal":{"name":"2010 35th IEEE Photovoltaic Specialists Conference","volume":"102 1","pages":"000493-000497"},"PeriodicalIF":0.0,"publicationDate":"2010-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82965417","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-06-20DOI: 10.1109/PVSC.2010.5616929
R. Dhere, M. Bonnet-eymard, Emilie Charlet, E. Peter, J. Duenow, H. Moutinho, Jian V. Li, M. Scott, D. Albin, T. Gessert
In this paper, we present our work on devices fabricated using CdTe films deposited by close-spaced sublimation using substrate temperatures in the range of 450° to 620° C. We studied devices prepared on Saint-Gobain soda lime SGG Diamant and Corning 7059 borosilicate glass substrates. We used four types of contact: SnO2:F, ITO, CTO, and Saint-Gobain AZO with and without high-resistivity buffer layers. We used a variety of buffer layers: undoped SnO2, zinc tin oxide (ZTO), and proprietary Saint-Gobain buffer layers. A buffer layer is crucial for devices using CTO and AZO as the front contact. For AZO layers developed by Saint-Gobain, we achieved 9% efficiency without a buffer layer and over 12% efficiency using buffer layers when CdTe films are deposited below 500° C. We used standard current density-voltage and quantum efficiency analysis to determine the device parameters.
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