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Achieving an Efficiency Exceeding 10% for Fullerene‐based Polymer Solar Cells Employing a Thick Active Layer via Tuning Molecular Weight
Author(s) -
Li Zelin,
Yang Dalei,
Zhao Xiaoli,
Zhang Tong,
Zhang Jidong,
Yang Xiaoniu
Publication year - 2018
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201705257
Subject(s) - active layer , materials science , energy conversion efficiency , crystallinity , layer (electronics) , optoelectronics , polymer , polymer solar cell , fullerene , electron mobility , nanotechnology , composite material , organic chemistry , chemistry , thin film transistor
Recently, the influence of molecular weight ( M n ) on the performance of polymer solar cells (PSCs) is widely investigated. However, the dependence of optimal thickness of active layer for PSCs on M n is not reported yet, which is vital to the solution printing technology. In this work, the effect of M n on the efficiency and especially optimal thickness of the active layer for PBTIBDTT‐S‐based PSCs is systematically studied. The device efficiency improves significantly as the M n increases from 12 to 38 kDa, and a remarkable efficiency of 10.1% is achieved, which is among the top efficiencies of wide‐bandgap polymer:fullerene PSCs. Furthermore, the optimal thickness of the active layer is also greatly increased from 62 to 210 nm with increased M n . Therefore, a device employing a thick (>200 nm) active layer with power conversion efficiency exceeding 10% is achieved by manipulating M n . This exciting result is attributed to both the improved crystallinity, thus hole mobility, and preferable polymer orientation, thus morphology of active layer. These findings, for the first time, highlight the significant impact of M n on the optimal thickness of active layer for PSCs and provide a facile way to further improve the performance of PSCs employing a thick active layer.