Effects of Cyano-Substituents on the Molecular Packing Structures of Conjugated Polymers for Bulk-Heterojunction Solar Cells
SCIE
SCOPUS
- Title
- Effects of Cyano-Substituents on the Molecular Packing Structures of Conjugated Polymers for Bulk-Heterojunction Solar Cells
- Authors
- Cha, H; Kim, HN; An, TK; Kang, MS; Kwon, SK; Kim, YH; Park, CE
- Date Issued
- 2014-09-24
- Publisher
- AMER CHEMICAL SOC
- Abstract
- The molecular packing structures of two conjugated polymers based on alkoxy naphthalene, one with cyano-substituents and one without, have been investigated to determine the effects of electron-withdrawing cyano-groups on the performance of bulk-heterojunction solar cells. The substituted cyano-groups facilitate the self-assembly of the polymer chains, and the cyano-substituted polymer:PC71BM blend exhibits enhanced exciton dissociation to PC7IBM. Moreover, the electron-withdrawing cyano-groups lower the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels of the conjugated polymer, which leads to a higher open circuit voltage (V-OC) and a lower energy loss during electron transfer from the donor to the acceptor. A bulk-heterojunction device fabricated with the cyano-substituted polymer:PC71BM blend has a higher V-OC (0.89 V), a higher fill factor (FF) (51.4%), and a lower short circuit current (J(SC) (7.4 mA/cm(2)) than that of the noncyano-substituted polymer:PC71BM blend under AM 1.5G illumination with an intensity of 100 mW cm(-2). Thus, the cyano-substitution of conjugated polymers may be an effective strategy for optimizing the domain size and crystallinity of the polymer:PC71BM blend, and for increasing V-OC by tuning the HOMO and LUMO energy levels of the conjugated polymer.
- Keywords
- electron-withdrawing cyano-groups; alkoxy naphthalene derivative; morphology control; conjugated polymer; phase separation; organic photovoltaics; OPEN-CIRCUIT VOLTAGE; NON-GEMINATE RECOMBINATION; FIELD-EFFECT TRANSISTORS; LOW-BANDGAP POLYMER; PHOTOVOLTAIC CELLS; FLUORINE SUBSTITUENTS; EFFICIENCY; DONOR; BLENDS; PERFORMANCE
- URI
- https://oasis.postech.ac.kr/handle/2014.oak/14105
- DOI
- 10.1021/AM502795Y
- ISSN
- 1944-8244
- Article Type
- Article
- Citation
- ACS APPLIED MATERIALS & INTERFACES, vol. 6, no. 18, page. 15774 - 15782, 2014-09-24
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