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Impact of symmetry-breaking of non-fullerene acceptors for efficient and stable organic solar cells

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Abstract
The concurrent enhancement of short-circuit current (J(SC)) and open-circuit voltage (V-OC) is a key problem in the preparation of efficient organic solar cells (OSCs). In this paper, we report efficient and stable OSCs based on an asymmetric non-fullerene acceptor (NFA) IPC-BEH-IC2F. The NFA consists of a weak electron-donor core dithienothiophen[3,2-b]-pyrrolobenzothiadiazole (BEH) and two kinds of strong electron-acceptor (A) units [9H-indeno[1,2-b]pyrazine-2,3-dicarbonitrile (IPC) with a tricyclic fused system and 2-(5,6-difluoro-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (IC2F)]. For comparison, the symmetric NFAs IPC-BEH-IPC and IC2F-BEH-IC2F were characterised. The kind of flanking A unit significantly affects the light absorption features and electronic structures of the NFAs. The asymmetric IPC-BEH-IC2F has the highest extinction coefficient among the three NFAs owing to its strong dipole moment and highly crystalline feature. Its highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels lie between those of the IPC-BEH-IPC and IC2F-BEH-IC2F molecules. The IPC group also promotes molecular packing through the tricyclic pi-conjugated system and achieves increased crystallinity compared to that of the IC2F group. Inverted-type photovoltaic devices based on p-type polymer:NFA blends with PBDB-T and PM6 polymers as p-type polymers were fabricated. Among all these devices, the PBDB-T:IPC-BEH-IC2F blend device displayed the best photovoltaic properties because the IPC unit provides balanced electronic and morphological characteristics. More importantly, the PBDB-T:IPC-BEH-IC2F-based device exhibited the best long-term stability owing to the strongly interacting IPC moiety and the densely packed PBDB-T:IPC-BEH-IC2F film. These results demonstrate that asymmetric structural modifications of NFAs are an effective way for simultaneously improving the photovoltaic performance and stability of OSCs.
Author(s)
Peddaboodi GopikrishnaHuijeong Choi김도희Jun Ho HwangYoungwan LeeHyeonwoo JungGyeonghwa YuTelugu Bhim RajuEunji LeeYoungu Lee조신욱BongSoo Kim
Issued Date
2021
Type
Article
DOI
10.1039/d1sc04153c
URI
https://oak.ulsan.ac.kr/handle/2021.oak/8999
https://ulsan-primo.hosted.exlibrisgroup.com/primo-explore/fulldisplay?docid=TN_cdi_rsc_primary_d1sc04153c&context=PC&vid=ULSAN&lang=ko_KR&search_scope=default_scope&adaptor=primo_central_multiple_fe&tab=default_tab&query=any,contains,Impact%20of%20symmetry-breaking%20of%20non-fullerene%20acceptors%20for%20efficient%20and%20stable%20organic%20solar%20cells&offset=0&pcAvailability=true
Publisher
CHEMICAL SCIENCE
Location
영국
Language
영어
ISSN
2041-6520
Citation Volume
12
Citation Number
42
Citation Start Page
14083
Citation End Page
14097
Appears in Collections:
Engineering > Material Engineering
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