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Organic Amines as Targeting Stabilizer at the Polymer/Fullerene Interface for Polymer:PC 61 BM Solar Cells
Author(s) -
Li Zerui,
Yan Lingpeng,
Shan Jiankai,
Gu Huimin,
Lin Yi,
Wang Yaling,
Tan Hongwei,
Ma Chang-Qi
Publication year - 2020
Publication title -
energy technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.91
H-Index - 44
eISSN - 2194-4296
pISSN - 2194-4288
DOI - 10.1002/ente.202000266
Subject(s) - piperazine , polymer , fullerene , materials science , electron paramagnetic resonance , dithiocarbamate , polymer chemistry , chemistry , nuclear chemistry , photochemistry , organic chemistry , nuclear magnetic resonance , physics
Herein, it is demonstrated that a small amount (0.05% in weight ratio) of polyethyleneimine (PEI) can effectively suppress the “burn‐in” degradation of both PTB7‐Th:PC 61 BM and P3HT:PC 61 BM cells, similar to the piperazine derivatives, suggesting that organic amines can serve as universal stabilizer in polymer:PC 61 BM solar cells. Light‐induced electron spin resonance (LESR) spectroscopy measurement shows a higher ESR signal intensity of PC 61 BM anions in 0.2% PEI‐doped film than in 1% piperazine‐doped film. Moreover, no piperazine is detected in a 10% (w/w) piperazine‐doped film by gas chromatography–mass spectrometry (GSMS). These results suggest that the residual piperazine in the blend film is very low, which can be understood by the high volatility of piperazine. Quantum calculations are performed on the intermolecular binding energy ( E B ) between polymer (using model repeating units), PC 61 BM, and piperazine molecules. Results reveal that piperazine prefers to localize at the polymer:fullerene interface by complexing with PC 61 BM (in P3HT:PC 61 BM) or PTB7‐Th (in PTB7‐Th:PC 61 BM system), which indicates that the photo dimerization of PC 61 BM which causes the “burn‐in” degradation of polymer:fullerene solar cells mainly happens at the donor/acceptor interface, and the organic amine serves as the targeting stabilizer at the interface.