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A 1 ‐A 2 Type Wide Bandgap Polymers for High‐Performance Polymer Solar Cells: Energy Loss and Morphology
Author(s) -
An Yongkang,
Liao Xunfan,
Chen Lie,
Xie Qian,
Zhang Ming,
Huang Bin,
Liao Zhihui,
Guo Hui,
Jazib Ali,
Han Jihui,
Liu Feng,
Jen Alex K.Y.,
Chen Yiwang
Publication year - 2019
Publication title -
solar rrl
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.544
H-Index - 37
ISSN - 2367-198X
DOI - 10.1002/solr.201800291
Subject(s) - materials science , acceptor , polymer , polymer solar cell , band gap , stacking , conjugated system , homo/lumo , energy conversion efficiency , monomer , electron acceptor , photoluminescence , optoelectronics , open circuit voltage , short circuit , photochemistry , chemical engineering , nanotechnology , voltage , molecule , organic chemistry , chemistry , composite material , electrical engineering , physics , engineering , condensed matter physics
Introducing electron‐withdrawing groups onto donor‐acceptor (D‐A) type conjugated materials is a commonly used method for lowering their highest occupied molecular orbital (HOMO) energy level to achieve higher open circuit voltage ( V oc ) in polymer solar cells (PSCs). However, this method is rather costly due to the tedious synthesis and low yield involved in preparing the target monomers. Here, a novel design concept of using two different acceptor units to construct acceptor 1 ‐acceptor 2 (A 1 ‐A 2 ) type polymers with a deep HOMO level is proposed. Two A 1 ‐A 2 type wide bandgap (WBG) polymers, PB24‐3TDC and PB68‐3TDC, were designed for PSCs. The developed polymers possess proper energy levels and complementary absorption with an efficient electron acceptor ITIC‐Th. More importantly, by slightly regulating the alkyl side‐chains, molecular stacking and photoluminescence (PL) emission energy loss of polymers can be alternated significantly. As a result, tuned V oc from 0.9 to 1.0 V and short‐circuit current ( J sc ) from 9.4 to 17.0 mA cm −2 can be achieved. The device based on PB24‐3TDC:ITIC‐Th exhibits a higher power conversion efficiency (PCE) of 10.3% compared to PB68‐3TDC:ITIC‐Th based device with a PCE of 7.88%. These results show that the design concept of A 1 ‐A 2 type polymer donors have great potential for blending with non‐fullerene acceptors for achieving high performance PSCs.