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Terthieno[3,2‐ b ]Thiophene (6T) Based Low Bandgap Fused‐Ring Electron Acceptor for Highly Efficient Solar Cells with a High Short‐Circuit Current Density and Low Open‐Circuit Voltage Loss
Author(s) -
Shi Xueliang,
Chen Jingde,
Gao Ke,
Zuo Lijian,
Yao Zhaoyang,
Liu Feng,
Tang Jianxin,
Jen Alex K.Y.
Publication year - 2018
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201702831
Subject(s) - materials science , energy conversion efficiency , thiophene , open circuit voltage , band gap , acceptor , electron acceptor , optoelectronics , conjugated system , organic solar cell , short circuit , annealing (glass) , polymer solar cell , solar cell , voltage , photochemistry , polymer , organic chemistry , condensed matter physics , chemistry , electrical engineering , physics , composite material , engineering
Abstract A terthieno[3,2‐ b ]thiophene ( 6T ) based fused‐ring low bandgap electron acceptor, 6TIC , is designed and synthesized for highly efficient nonfullerene solar cells. The chemical, optical, and physical properties, device characteristics, and film morphology of 6TIC are intensively studied. 6TIC shows a narrow bandgap with band edge reaching 905 nm due to the electron‐rich π‐conjugated 6T core and reduced resonance stabilization energy. The rigid, π‐conjugated 6T also offers lower reorganization energy to facilitate very low V OC loss in the 6TIC system. The analysis of film morphology shows that PTB7‐Th and 6TIC can form crystalline domains and a bicontinuous network. These domains are enlarged when thermal annealing is applied. Consequently, the device based on PTB7‐Th : 6TIC exhibits a high power conversion efficiency (PCE) of 11.07% with a high J SC > 20 mA cm −2 and a high V OC of 0.83 V with a relatively low V OC loss (≈0.55 V). Moreover, a semitransparent solar cell based on PTB7‐Th : 6TIC exhibits a relatively high PCE (7.62%). The device can have combined high PCE and high J SC is quite rare for organic solar cells.