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- Title
Over 13% Efficiency Ternary Nonfullerene Polymer Solar Cells with Tilted Up Absorption Edge by Incorporating a Medium Bandgap Acceptor.
- Authors
Zhang, Miao; Xiao, Zuo; Gao, Wei; Liu, Qishi; Jin, Ke; Wang, Wenbin; Mi, Yang; An, Qiaoshi; Ma, Xiaoling; Liu, Xinfeng; Yang, Chuluo; Ding, Liming; Zhang, Fujun
- Abstract
Efficient ternary polymer solar cells (PSCs) are prepared with poly‐[4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)benzo[1,2‐b:4,5‐b′] dithiophene‐co‐3fluorothieno[3,4‐b]thiophene‐2‐carboxylate] (PTB7‐Th):COi8DFIC as host system and medium bandgap material BDTThIT‐4F as the third component. The power conversion efficiency of PSCs can be increased from 11.47% to 13.08% by incorporating 20 wt% BDTThIT‐4F in acceptors, along with the simultaneously improved three key photovoltaic parameters. The absorption edge of ternary blend films can be tilted up in long wavelength range by incorporating appropriate BDTThIT‐4F, although the bandgap of BDTThIT‐4F is wider than that of COi8DFIC, leading to the extended external quantum efficiency spectra of ternary PSCs. The tilted up absorption edge of blend films should be attributed to the variation of COi8DFIC molecular arrangement, which can be well demonstrated from the transient and steady absorption spectra of blend films with different donors and acceptors. A new ground state bleach signal can be clearly observed in transient absorption spectra of the optimized ternary blend films, which may be due to the varied COi8DFIC molecular energy levels by incorporating BDTThIT‐4F. Meanwhile, the lifetimes on excited states are increased in the ternary blend films, which is beneficial to exciton dissociation for improving the performance of ternary PSCs. Efficient ternary non‐fullerene polymer solar cells (PSCs) are fabricated with poly‐[4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)benzo[1,2‐b:4,5‐b′] dithiophene‐co‐3‐fluorothieno[3,4‐b]thiophene‐2‐carboxylate] (PTB7‐Th):COi8DFIC:BDTThIT‐4F as active layers. The power conversion efficiency is increased from 11.47% to 13.08% by incorporating 20 wt% BDTThIT‐4F in acceptors, which is attributed to the tilted up absorption edge and the optimized phase separation of ternary active layers.
- Subjects
FULLERENE polymers; SOLAR cells; ABSORPTION; BAND gaps; PHOTOVOLTAIC power generation
- Publication
Advanced Energy Materials, 2018, Vol 8, Issue 30, pN.PAG
- ISSN
1614-6832
- Publication type
Article
- DOI
10.1002/aenm.201801968