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2. A Design Based on Stair-case Band Alignment of Electron Transport Layer for Improving Performance and Stability in Planar Perovskite Solar Cells

Author

Wu, Shang-Hsuan, Lin, Ming-Yi, Chang, Sheng-Hao, Tu, Wei-Chen, Chu, Chih-Wei, and Chang, Yia-Chung

Subjects
Physics - Applied Physics
Abstract

Among the n-type metal oxide materials used in the planar perovskite solar cells, zinc oxide (ZnO) is a promising candidate to replace titanium dioxide (TiO2) due to its relatively high electron mobility, high transparency, and versatile nanostructures. Here, we present the application of low temperature solution processed ZnO/Al-doped ZnO (AZO) bilayer thin film as electron transport layers (ETLs) in the inverted perovskite solar cells, which provide a stair-case band profile. Experimental results revealed that the power conversion efficiency (PCE) of perovskite solar cells were significantly increased from 12.25 to 16.07% by employing the AZO thin film as the buffer layer. Meanwhile, the short-circuit current density (Jsc), open-circuit voltage (Voc), and fill factor (FF) were improved to 20.58 mA/cm2, 1.09V, and 71.6%, respectively. The enhancement in performance is attributed to the modified interface in ETL with stair-case band alignment of ZnO/AZO/CH3NH3PbI3, which allows more efficient extraction of photogenerated electrons in the CH3NH3PbI3 active layer. Thus, it is demonstrated that the ZnO/AZO bilayer ETLs would benefit the electron extraction and contribute in enhancing the performance of perovskite solar cells.

Published
2017

3. Precision Medicine for Apical Lesions and Peri-Endo Combined Lesions Based on Transfer Learning Using Periapical Radiographs.

Author

Wu, Pei-Yi, Mao, Yi-Cheng, Lin, Yuan-Jin, Li, Xin-Hua, Ku, Li-Tzu, Li, Kuo-Chen, Chen, Chiung-An, Chen, Tsung-Yi, Chen, Shih-Lun, Tu, Wei-Chen, and Abu, Patricia Angela R.

Subjects
TOOTH roots, TECHNOLOGICAL innovations, CONVOLUTIONAL neural networks, IMAGE intensifiers, DATABASES, HISTOGRAMS
Abstract

An apical lesion is caused by bacteria invading the tooth apex through caries. Periodontal disease is caused by plaque accumulation. Peri-endo combined lesions include both diseases and significantly affect dental prognosis. The lack of clear symptoms in the early stages of onset makes diagnosis challenging, and delayed treatment can lead to the spread of symptoms. Early infection detection is crucial for preventing complications. PAs used as the database were provided by Chang Gung Memorial Medical Center, Taoyuan, Taiwan, with permission from the Institutional Review Board (IRB): 02002030B0. The tooth apex image enhancement method is a new technology in PA detection. This image enhancement method is used with convolutional neural networks (CNN) to classify apical lesions, peri-endo combined lesions, and asymptomatic cases, and to compare with You Only Look Once-v8-Oriented Bounding Box (YOLOv8-OBB) disease detection results. The contributions lie in the utilization of database augmentation and adaptive histogram equalization on individual tooth images, achieving the highest comprehensive validation accuracy of 95.23% with the ConvNextv2 model. Furthermore, the CNN outperformed YOLOv8 in identifying apical lesions, achieving an F1-Score of 92.45%. For the classification of peri-endo combined lesions, CNN attained the highest F1-Score of 96.49%, whereas YOLOv8 scored 88.49%. [ABSTRACT FROM AUTHOR]

Published
2024
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6. Efficiency Enhancement of Silicon Heterojunction Solar Cells via Photon Management Using Graphene Quantum Dot as Downconverters

Author

Tsai, Meng-Lin, Tu, Wei-Chen, Tang, Libin, Wei, Tzu-Chiao, Wei, Wan-Rou, Lau, Shu Ping, Chen, Lih-Juann, and He, Jr-Hau

Subjects
Physical Sciences, Engineering, Materials Engineering, Nanotechnology, graphene, heterojunction, photovoltaic, quantum dot, solar cells, Nanoscience & Nanotechnology
Abstract

By employing graphene quantum dots (GQDs), we have achieved a high efficiency of 16.55% in n-type Si heterojunction solar cells. The efficiency enhancement is based on the photon downconversion phenomenon of GQDs to make more photons absorbed in the depletion region for effective carrier separation, leading to the enhanced photovoltaic effect. The short circuit current and the fill factor are increased from 35.31 to 37.47 mA/cm(2) and 70.29% to 72.51%, respectively. The work demonstrated here holds the promise for incorporating graphene-based materials in commercially available solar devices for developing ultrahigh efficiency photovoltaic cells in the future.

Published
2016

9. Multifunctional and High‐Performance FAPBI3 Quantum Dots/Graphene UV Photodetectors by the Modulation of Photoconductivity.

Author

Shen, Jun‐Hao, Yu, Xiu‐Qi, and Tu, Wei‐Chen

Subjects
QUANTUM dots, PHOTOCONDUCTIVITY, PHOTODETECTORS, GRAPHENE, CHEMICAL vapor deposition, ULTRAVIOLET radiation
Abstract

Low‐dimensional devices with different photoconductive effects attract much attention in optoelectronics. In this work, negative photoconductivity (NPC) monolayer graphene photodetectors are fabricated by chemical vapor deposition (CVD), and a positive photoconductivity (PPC) photodetector is realized by decorating perovskite FAPbI3 quantum dots prepared by a simple and cost‐effective non‐polar solvent synthesis method on a graphene surface. The graphene‐based photodetector exhibits an NPC characteristic, which is attributed to the absorption and desorption of water molecules on the graphene surface. The responsivity of the photodetector with an NPC characteristic is −0.86 A W−1 under intense ultraviolet light irradiation, and the detectivity is −2.45 × 109 Jones. The FAPbI3 quantum dots/graphene photodetector with a PPC feature has a responsivity of 8.03 A W−1 and a detectivity of 1.89 × 1010 Jones under the irradiation of ultraviolet light of 365 nm and 55.3 mW cm−2 intensity. Due to the intense light absorption of perovskite combined with the extremely high mobility of graphene, photodetectors have high exciton separation and photocurrents when the devices are irradiated by ultraviolet light. Individual photodetectors are successfully created with NPC and PPC effects; the critical analysis for the different photoconductive mechanisms is provided, which will benefit the development of future multifunctional systems. [ABSTRACT FROM AUTHOR]

Published
2023
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35. A Design Based on a Charge-Transfer Bilayer as an Electron Transport Layer for Improving the Performance and Stability in Planar Perovskite Solar Cells

Author

Wu, Shang-Hsuan, Lin, Ming-Yi, Chang, Sheng-Hao, Tu, Wei-Chen, Chu, Chih-Wei, and Chang, Yia-Chung

Abstract

A highly efficient electron transport layer (ETL) is an essential constituent for good performance and stability in planar perovskite solar cells. Among n-type metal oxide materials, zinc oxide (ZnO) is a promising candidate for an electron transport layer due to its relatively high electron mobility, high transparency, and versatile nanostructures. However, it was found that several disadvantages could occur at the ZnO/perovskite interface, such as decomposition of CH3NH3PbI3and poorly aligned energy levels. To overcome these issues, we present a design based on staircase band alignment of a low-temperature solution-processed ZnO/Al-doped ZnO (AZO) bilayer thin film as electron transport layers in planar perovskite solar cells. Experimental results revealed that the power conversion efficiency (PCE) of perovskite solar cells was significantly increased from 12.3% to 16.1% by employing the AZO thin film as the buffer layer. Meanwhile, the short-circuit current density (Jsc), open-circuit voltage (Voc), and fill factor (FF) were improved to 20.6 mA/cm2, 1.09 V, and 71.6%, respectively. The enhancement in performance is attributed to the modified interface in the ETL with staircase band alignment of ZnO/AZO/CH3NH3PbI3, which allows more efficient extraction of photogenerated electrons in the CH3NH3PbI3active layer. Our studies demonstrated that the solution-processed ZnO/AZO bilayer ETLs provide a promising new approach for the development of low-cost, high-performance, and stable planar perovskite solar cells.

Published
2024
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36. Worldwide Outdoor Round Robin Study Of Organic Photovoltaic Devices And Modules

Author

Madsen, Morten V., Gevorgyan, Suren A., Pacios, R., Ajuria, J., Etxebarria, I., Kettle, Jeff, Bristow, Noel D., Neophytou, Marios, Choulis, Stelios A., Roman, Lucimara Stolz, Yohannes, Teketel, Cester, Andrea, Cheng, Pei, Zhan, Xiaowei, Wu, Jiang, Xie, Zhiyuan, Tu, Wei-Chen, He, Jr-Hau, Fell, Christopher J., and Anderson, Kenrick

Abstract

Accurate characterization and reporting of organic photovoltaic (OPV) device performance reniains one of the important challenges in the field. The large spread among the efficiencies of devices with the same structure reported by different groups is significantly caused by different procedures and equipment used during testing. The presented article addresses this issue by offering a new method of device testing using "suitcase sample" approach combined with outdoor testing that limits the diversity of the equipment, and a strict measurement protocol. A round robin outdoor characterization of roll-to-roll coated OPV cells and modules conducted among 46 laboratories worldwide is presented, where the samples and the testing equipment were integrated in a compact suitcase that served both as a sample transportation tool and as a holder and test equipment during testing. In addition, an internet based coordination was used via plasticphotovoltaics.org that allowed fast and efficient communication among participants and provided a controlled reporting format for the results that eased the analysis of the data. The reported deviations among the laboratories were limited to 5% when compared to the Si reference device integrated in the suitcase and were up to 8% when calculated using the local irradiance data. Therefore, this method offers a fast, cheap and efficient tool for sample sharing and testing that allows conducting outdoor measurements of OPV devices in a reproducible manner. (C) 2014 Elsevier B.V. All rights reserved.

Published
2014

44. Worldwide outdoor round robin study of organic photovoltaic devices and modules

Author

Madsen, Morten V, Gevorgyan, Suren A, Pacios, R, Ajuria, J, Etxebarria, I, Kettle, Jeff, Bristow, Noel D, Neophytou, Marios, Choulis, Stelios A, Stolz Roman, Lucimara, Yohannes, Teketel, Cester, Andrea, Cheng, Pei, Zhan, Xiaowei, Wu, Jiang, Xie, Zhiyuan, Tu, Wei-Chen, He, Jr-Hau, Fell, Christopher J, Anderson, Kenrick, Hermenau, Martin, Bartesaghi, Davide, Jan Anton Koster, L, Machui, Florian, Gonzalez-Valls, Irene, Lira-Cantu, Monica, Khlyabich, Petr P, Thompson, Barry C, Gupta, Ritu, Shanmugam, Kiruthika, Kulkarni, Giridhar U, Galagan, Yulia, Urbina, Antonio, Abad, Jose, Roesch, Roland, Hoppe, Harald, Morvillo, P, Bobeico, E, Panaitescu, Eugen, Menon, Latika, Luo, Qun, Wu, Zhenwu, Ma, Changqii, Hambarian, Artak, Melikyan, Varuzhan, Hambsch, M, Burn, Paul L, Meredith, Paul, Rath, Thomas, Dunst, Sebastian, Trimmel, Gregor, Bardizza, Giorgio, Mullejans, Harald, Goryachev, A E, Misra, Ravi K, Katz, Eugene A, Takagi, Katsuhiko, Magaino, Shinichi, Saito, Hidenori, Aoki, Daisuke, Sommeling, Paul M, Kroon, Jan M, Vangerven, Tim, Manca, Jean, Kesters, Jurgen, Maes, Wouter, Bobkova, Olga D, Trukhanov, Vasily A, Paraschuk, Dmitry Yu, Castro, Fernando A, Blakesley, James, Tuladhar, Sachetan M, Rohr, Jason Alexander, Nelson, Jenny, Xia, Jiangbin, Parlak, Elif Alturk, Tumay, Tulay Alsi, Egelhaaf, Hans-Joachim, Tanenbaum, David M, Ferguson, Gretta Mae, Carpenter, Robert, Chen, Hongzheng, Zimmermann, Birger, Hirsch, Lionel, Wantz, Guillaume, Sun, Ziqi, Singh, Pradeep, Bapat, Chaitnya, Offermans, Ton, Krebs, Frederik C, Madsen, Morten V, Gevorgyan, Suren A, Pacios, R, Ajuria, J, Etxebarria, I, Kettle, Jeff, Bristow, Noel D, Neophytou, Marios, Choulis, Stelios A, Stolz Roman, Lucimara, Yohannes, Teketel, Cester, Andrea, Cheng, Pei, Zhan, Xiaowei, Wu, Jiang, Xie, Zhiyuan, Tu, Wei-Chen, He, Jr-Hau, Fell, Christopher J, Anderson, Kenrick, Hermenau, Martin, Bartesaghi, Davide, Jan Anton Koster, L, Machui, Florian, Gonzalez-Valls, Irene, Lira-Cantu, Monica, Khlyabich, Petr P, Thompson, Barry C, Gupta, Ritu, Shanmugam, Kiruthika, Kulkarni, Giridhar U, Galagan, Yulia, Urbina, Antonio, Abad, Jose, Roesch, Roland, Hoppe, Harald, Morvillo, P, Bobeico, E, Panaitescu, Eugen, Menon, Latika, Luo, Qun, Wu, Zhenwu, Ma, Changqii, Hambarian, Artak, Melikyan, Varuzhan, Hambsch, M, Burn, Paul L, Meredith, Paul, Rath, Thomas, Dunst, Sebastian, Trimmel, Gregor, Bardizza, Giorgio, Mullejans, Harald, Goryachev, A E, Misra, Ravi K, Katz, Eugene A, Takagi, Katsuhiko, Magaino, Shinichi, Saito, Hidenori, Aoki, Daisuke, Sommeling, Paul M, Kroon, Jan M, Vangerven, Tim, Manca, Jean, Kesters, Jurgen, Maes, Wouter, Bobkova, Olga D, Trukhanov, Vasily A, Paraschuk, Dmitry Yu, Castro, Fernando A, Blakesley, James, Tuladhar, Sachetan M, Rohr, Jason Alexander, Nelson, Jenny, Xia, Jiangbin, Parlak, Elif Alturk, Tumay, Tulay Alsi, Egelhaaf, Hans-Joachim, Tanenbaum, David M, Ferguson, Gretta Mae, Carpenter, Robert, Chen, Hongzheng, Zimmermann, Birger, Hirsch, Lionel, Wantz, Guillaume, Sun, Ziqi, Singh, Pradeep, Bapat, Chaitnya, Offermans, Ton, and Krebs, Frederik C

Abstract

Accurate characterization and reporting of organic photovoltaic (OPV) device performance remains one of the important challenges in the field. The large spread among the efficiencies of devices with the same structure reported by different groups is significantly caused by different procedures and equipment used during testing. The presented article addresses this issue by offering a new method of device testing using "suitcase sample" approach combined with outdoor testing that limits the diversity of the equipment, and a strict measurement protocol. A round robin outdoor characterization of roll-to-roll coated OPV cells and modules conducted among 46 laboratories worldwide is presented, where the samples and the testing equipment were integrated in a compact suitcase that served both as a sample transportation tool and as a holder and test equipment during testing. In addition, an internet based coordination was used via plasticphotovoltaics.org that allowed fast and efficient communication among participants and provided a controlled reporting format for the results that eased the analysis of the data. The reported deviations among the laboratories were limited to 5% when compared to the Si reference device integrated in the suitcase and were up to 8% when calculated using the local irradiance data. Therefore, this method offers a fast, cheap and efficient tool for sample sharing and testing that allows conducting outdoor measurements of OPV devices in a reproducible manner.

Published
2014

45. Worldwide outdoor round robin study of organic photovoltaic devices and modules

Author

Madsen, Morten V., primary, Gevorgyan, Suren A., additional, Pacios, R., additional, Ajuria, J., additional, Etxebarria, I., additional, Kettle, Jeff, additional, Bristow, Noel D., additional, Neophytou, Marios, additional, Choulis, Stelios A., additional, Stolz Roman, Lucimara, additional, Yohannes, Teketel, additional, Cester, Andrea, additional, Cheng, Pei, additional, Zhan, Xiaowei, additional, Wu, Jiang, additional, Xie, Zhiyuan, additional, Tu, Wei-Chen, additional, He, Jr-Hau, additional, Fell, Christopher J, additional, Anderson, Kenrick, additional, Hermenau, Martin, additional, Bartesaghi, Davide, additional, Jan Anton Koster, L., additional, Machui, Florian, additional, González-Valls, Irene, additional, Lira-Cantu, Monica, additional, Khlyabich, Petr P., additional, Thompson, Barry C., additional, Gupta, Ritu, additional, Shanmugam, Kiruthika, additional, Kulkarni, Giridhar U., additional, Galagan, Yulia, additional, Urbina, Antonio, additional, Abad, Jose, additional, Roesch, Roland, additional, Hoppe, Harald, additional, Morvillo, P., additional, Bobeico, E., additional, Panaitescu, Eugen, additional, Menon, Latika, additional, Luo, Qun, additional, Wu, Zhenwu, additional, Ma, Changqi, additional, Hambarian, Artak, additional, Melikyan, Varuzhan, additional, Hambsch, M., additional, Burn, Paul L., additional, Meredith, Paul, additional, Rath, Thomas, additional, Dunst, Sebastian, additional, Trimmel, Gregor, additional, Bardizza, Giorgio, additional, Müllejans, Harald, additional, Goryachev, A.E., additional, Misra, Ravi K., additional, Katz, Eugene A., additional, Takagi, Katsuhiko, additional, Magaino, Shinichi, additional, Saito, Hidenori, additional, Aoki, Daisuke, additional, Sommeling, Paul M., additional, Kroon, Jan M., additional, Vangerven, Tim, additional, Manca, Jean, additional, Kesters, Jurgen, additional, Maes, Wouter, additional, Bobkova, Olga D., additional, Trukhanov, Vasily A., additional, Paraschuk, Dmitry Yu., additional, Castro, Fernando A., additional, Blakesley, James, additional, Tuladhar, Sachetan M, additional, Alexander Röhr, Jason, additional, Nelson, Jenny, additional, Xia, Jiangbin, additional, Parlak, Elif Alturk, additional, Tumay, Tülay Aslı, additional, Egelhaaf, Hans-Joachim, additional, Tanenbaum, David M., additional, Mae Ferguson, Gretta, additional, Carpenter, Robert, additional, Chen, Hongzheng, additional, Zimmermann, Birger, additional, Hirsch, Lionel, additional, Wantz, Guillaume, additional, Sun, Ziqi, additional, Singh, Pradeep, additional, Bapat, Chaitnya, additional, Offermans, Ton, additional, and Krebs, Frederik C., additional

Published
2014
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