Efficient Semitransparent Solar Cells with High NIR Responsiveness Enabled by a Small‐Bandgap Electron Acceptor |
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| Authors: | Feng Liu Zichun Zhou Cheng Zhang Jianyun Zhang Qin Hu Thomas Vergote Feng Liu Thomas P. Russell Xiaozhang Zhu |
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| Affiliation: | 1. Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China;2. School of Chemistry and Chemical Engineering, University of Chinese Academy of Sciences, Beijing, China;3. Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA;4. Department of Physics and Astronomy, Shanghai Jiaotong University, Shanghai, China;5. Polymer Science and Engineering Department, University of Massachusetts, Amherst, MA, USA |
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| Abstract: | Inspired by the remarkable promotion of power conversion efficiency (PCE), commercial applications of organic photovoltaics (OPVs) can be foreseen in near future. One of the most promising applications is semitransparent (ST) solar cells that can be utilized in value‐added applications such as energy‐harvesting windows. However, the single‐junction STOPVs utilizing fullerene acceptors show relatively low PCEs of 4%–6% due to the limited sunlight absorption because it is a dilemma that more photons need to be harvested in UV–vis–near‐infrared (NIR) region to generate high photocurrent, which leads to the significant reduction of device transparency. This study describes the development of a new small‐bandgap electron‐acceptor material ATT‐2, which shows a strong NIR absorption between 600 and 940 nm with an E gopt of 1.32 eV. By combining with PTB7‐Th, the as‐cast OPVs yield PCEs of up to 9.58% with a fill factor of 0.63, an open‐circuit voltage of 0.73 V, and a very high short‐circuit current of 20.75 mA cm?2. Owing to the favorable complementary absorption of low‐bangap PTB7‐Th and small‐bandgap ATT‐2 in NIR region, the proof‐of‐concept STOPVs show the highest PCE of 7.7% so far reported for single‐junction STOPVs with a high transparency of 37%. |
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| Keywords: | near infrared nonfullerene acceptors power conversion efficiency semitransparent organic solar cells thieno[3,4‐b]thiophene |
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