Complementary Absorbing Star‐Shaped Small Molecules for the Preparation of Ternary Cascade Energy Structures in Organic Photovoltaic Cells |
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Authors: | Hyojung Cha Dae Sung Chung Suk Young Bae Min‐Jung Lee Tae Kyu An Jihun Hwang Kyung Hwan Kim Yun‐Hi Kim Dong Hoon Choi Chan Eon Park |
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Affiliation: | 1. Polymer Research Institute, Department of Chemical Engineering, Pohang University of Science Technology, Pohang, 790‐784, South Korea;2. Department of Chemical Engineering, Dong‐A University, Pusan, 604‐714, South Korea;3. Department of Chemistry, Research Institute for Natural Science, Korea University, Seoul, 136‐701, South Korea;4. Department of Chemistry, Gyeongsang National University, Jinju, 660–701, South Korea |
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Abstract: | Two anthracene‐based star‐shaped conjugated small molecules, 5′,5″‐(9,10‐bis((4‐hexylphenyl)ethynyl)anthracene‐2,6‐diyl)bis(5‐hexyl‐2,2′‐bithiophene), HBantHBT, and 5′,5″‐(9,10‐bis(phenylethynyl)anthracene‐2,6‐diyl)bis(5‐hexyl‐2,2′‐bithiophene), BantHBT, are used as electron‐cascade donor materials by incorporating them into organic photovoltaic cells prepared using a poly((5,5‐E‐alpha‐((2‐thienyl)methylene)‐2‐thiopheneacetonitrile)‐alt‐2,6‐[(1,5‐didecyloxy)naphthalene])) (PBTADN):[6,6]‐phenyl‐C71‐butyric acid methyl ester (PC71BM) blend. The small molecules penetrate the PBTADN:PC71BM blend layer to yield complementary absorption spectra through appropriate energy level alignment and optimal domain sizes for charge carrier transfer. A high short‐circuit current (JSC) and fill factor (FF) are obtained using solar cells prepared with the ternary blend. The highest photovoltaic performance of the PBTADN: BantHBT :PC71BM blend solar cells is characterized by a JSC of 11.0 mA cm?2, an open circuit voltage (VOC) of 0.91 V, a FF of 56.4%, and a power conversion efficiency (PCE) of 5.6% under AM1.5G illumination (with a high intensity of 100 mW?2). The effects of the small molecules on the ternary blend are investigated by comparison with the traditional poly(3‐hexylthiophene) (P3HT):[6,6]‐phenyl‐C61‐butyric acid methyl ester (PC61BM) system. |
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Keywords: | Ternary Cascade Energy Structure Photovoltaic Devices Charge Transport |
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