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Hole‐Transfer Dependence on Blend Morphology and Energy Level Alignment in Polymer: ITIC Photovoltaic Materials
Author(s) -
Eastham Nicholas D.,
Logsdon Jenna L.,
Manley Eric F.,
Aldrich Thomas J.,
Leonardi Matthew J.,
Wang Gang,
PowersRiggs Natalia E.,
Young Ryan M.,
Chen Lin X.,
Wasielewski Michael R.,
Melkonyan Ferdinand S.,
Chang Robert P. H.,
Marks Tobin J.
Publication year - 2018
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201704263
Subject(s) - materials science , photovoltaic system , polymer solar cell , fullerene , acceptor , polymer , organic solar cell , heterojunction , energy conversion efficiency , chemical engineering , optoelectronics , composite material , organic chemistry , ecology , chemistry , physics , engineering , biology , condensed matter physics
Bulk‐heterojunction organic photovoltaic materials containing nonfullerene acceptors (NFAs) have seen remarkable advances in the past year, finally surpassing fullerenes in performance. Indeed, acceptors based on indacenodithiophene (IDT) have become synonymous with high power conversion efficiencies (PCEs). Nevertheless, NFAs have yet to achieve fill factors (FFs) comparable to those of the highest‐performing fullerene‐based materials. To address this seeming anomaly, this study examines a high efficiency IDT‐based acceptor, ITIC , paired with three donor polymers known to achieve high FFs with fullerenes, PTPD3T , PBTI3T , and PBTSA3T . Excellent PCEs up to 8.43% are achieved from PTPD3T:ITIC blends, reflecting good charge transport, optimal morphology, and efficient ITIC to PTPD3T hole‐transfer, as observed by femtosecond transient absorption spectroscopy. Hole‐transfer is observed from ITIC to PBTI3T and PBTSA3T , but less efficiently, reflecting measurably inferior morphology and nonoptimal energy level alignment, resulting in PCEs of 5.34% and 4.65%, respectively. This work demonstrates the importance of proper morphology and kinetics of ITIC → donor polymer hole‐transfer in boosting the performance of polymer: ITIC photovoltaic bulk heterojunction blends.