Enhancement of the Photovoltaic Performance of CH3NH3PbI3 Perovskite Solar Cells through a Dichlorobenzene‐Functionalized Hole‐Transporting Material |
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| Authors: | Jin‐Wook Lee Sungmin Park Dr. Min Jae Ko Dr. Hae Jung Son Prof. Nam‐Gyu Park |
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| Affiliation: | 1. School of Chemical Engineering and Department of Energy Science, Sungkyunkwan University, Suwon, 440‐746 (Korea), Fax: (+82)?31‐290‐7241;2. Photoelectronic Hybrid Research Center, Korea Institute of Science and Technology, Seoul 136‐791 (Korea), Fax: (+82)?2‐958‐6649;3. Departmentof Chemistry, Korea University, Seoul 136‐713, (Korea) |
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| Abstract: | A dichlorobenzene‐functionalized hole‐transporting material (HTM) is developed for a CH3NH3PbI3‐based perovskite solar cell. Notwithstanding the similarity of the frontier molecular orbital energy levels, optical properties, and hole mobility between the functionalized HTM [a polymer composed of 2′‐butyloctyl‐4,6‐dibromo‐3‐fluorothieno[3,4‐b]thiophene‐2‐carboxylate (TT‐BO), 3′,4′‐dichlorobenzyl‐4,6‐dibromo‐3‐fluorothieno[3,4‐b]thiophene‐2‐carboxylate (TT‐DCB), and 2,6‐bis(trimethyltin)‐4,8‐bis(2‐ethylhexyloxy)benzo[1,2‐b:4,5‐b′]dithiophene (BDT‐EH), denoted PTB‐DCB21] and the nonfunctionalized polymer [a polymer composed of thieno[3,4‐b]thiophene (TT) and benzo[1,2‐b:4,5‐b′]dithiophene (BDT), denoted PTB‐BO], a higher power conversion efficiency for PTB‐DCB21 (8.7 %) than that for PTB‐BO (7.4 %) is achieved because of a higher photocurrent and voltage. The high efficiency is even obtained without including additives, such as lithium bis(trifluoromethanesulfonyl)imide and/or 4‐tert‐butylpyridine, that are commonly used to improve the conductivity of the HTM. Transient photocurrent–voltage studies show that the PTB‐DCB21‐based device exhibits faster electron transport and slower charge recombination; this might be related to better interfacial contact through intermolecular chemical interactions between the perovskite and the 3,4‐dichlorobenzyl group in PTB‐DCB21. |
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| Keywords: | electrochemistry polymers perovskite phases semiconductors solar cells |
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