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A Bromo‐Functionalized Conjugated Polymer as a Cross‐Linkable Anode Interlayer of Polymer Solar Cells
Author(s) -
Meng Bin,
Xie Zhiyuan,
Liu Jun,
Wang Lixiang
Publication year - 2016
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201501199
Subject(s) - active layer , side chain , materials science , polymer , polymer solar cell , conjugated system , anode , homo/lumo , chemical engineering , energy conversion efficiency , layer (electronics) , polymer chemistry , optoelectronics , nanotechnology , organic chemistry , composite material , electrode , chemistry , molecule , thin film transistor , engineering
A cross‐linkable conjugated polymer with bromo groups on the side chain has been developed and used as an anode interlayer to improve the active layer morphology and consequently enhance the device performance of polymer solar cells (PSCs). The polymer, PCDTBT‐Br , has cross‐linkable bromo groups attached to the side chain of a widely‐used donor polymer, poly[N‐9‐heptadecanyl‐2,7‐carbazole‐ alt ‐5,5‐(4,7‐di‐2‐thienyl‐2,1,3‐benzothiadiazole)] (PCDTBT). The pendant bromo groups do not significantly change the LUMO/HOMO energy levels and absorption spectrum of the PCDTBT polymer backbone. PDCTBT‐Br can crosslink under UV irradiation to give a robust film, which enables multilayer PSC device fabrication. Moreover, the much lower surface energy of PCDTBT‐Br (20.4 mJ m −2 ) compared to PEDOT:PSS (91.6 mJ m −2 ) is beneficial for achieving optimal active layer morphology. As a result, with PCDTBT:[6,6]‐phenyl‐C71 butyric acid methyl ester (PC 71 BM) as the active layer, the PSC device with PCDTBT‐Br as the underlying layer shows a power conversion efficiency (PCE) of 6.59 %, in comparison to a PCE of 5.86 % of the control device. The device performance enhancement is ascribed to the much improved phase separation with a fibrillar nanostructure in the active layer.