Naphtho[2,1‐b:3,4‐b′]dithiophene‐based Bulk Heterojunction Solar Cells: How Molecular Structure Influences Nanoscale Morphology and Photovoltaic Properties |
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Authors: | Yu Jin Kim Ye Rim Cheon Jang Yeol Back Prof Yun‐Hi Kim Dae Sung Chung Prof Chan Eon Park |
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Institution: | 1. POSTECH Organic Electronics Laboratory, Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam‐Ro, Nam‐Gu, Pohang, 790‐784 (Republic of Korea);2. Department of Chemistry & Research Institiute of Natural Science, Gyeongsang National University, Jinjudae‐Ro 501, Jin‐ju, 660‐701 (Republic of Korea);3. Department of School of Materials Science & Engineering and Research, Institute for Green Energy Convergence Technology (REGET), Gyeongsang National University, Jinjudae‐Ro 501, Jin‐ju, 660‐701 (Republic of Korea);4. School of Chemical Engineering and Materials Science, Chung‐Ang University, 84 Heukseok‐Ro, Dongjak‐Gu, Seoul, 156‐756 (Republic of Korea) |
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Abstract: | Organic bulk heterojunction photovoltaic devices based on a series of three naphtho2,1‐b:3,4‐b′]dithiophene (NDT) derivatives blended with phenyl‐C71‐butyric acid methyl ester were studied. These three derivatives, which have NDT units with various thiophene‐chain lengths, were employed as the donor polymers. The influence of their molecular structures on the correlation between their solar‐cell performances and their degree of crystallization was assessed. The grazing‐incidence angle X‐ray diffraction and atomic force microscopy results showed that the three derivatives exhibit three distinct nanoscale morphologies. We correlated these morphologies with the device physics by determining the J–V characteristics and the hole and electron mobilities of the devices. On the basis of our results, we propose new rules for the design of future generations of NDT‐based polymers for use in bulk heterojunction solar cells. |
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Keywords: | bulk heterojunction nanoscale morphology organic solar cells polymers X‐ray diffraction |
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