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Organic Amines as Targeting Stabilizer at the Polymer/Fullerene Interface for Polymer:PC <sub/>61</sub> BM Solar Cells
摘要： 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:PC61BM and P3HT:PC61BM cells, similar to the piperazine derivatives, suggesting that organic amines can serve as universal stabilizer in polymer:PC61BM solar cells. Light-induced electron spin resonance (LESR) spectroscopy measurement shows a higher ESR signal intensity of PC61BM 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 (GS─MS). 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 (EB) between polymer (using model repeating units), PC61BM, and piperazine molecules. Results reveal that piperazine prefers to localize at the polymer:fullerene interface by complexing with PC61BM (in P3HT:PC61BM) or PTB7-Th (in PTB7-Th:PC61BM system), which indicates that the photo dimerization of PC61BM 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.
关键词： quantum calculations,polymer solar cells,organic amines,stabilizers
更新于2025-09-23 15:21:01
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Ultrafast Nonadiabatic Cascade and Subsequent Photofragmentation of Extreme Ultraviolet Excited Caffeine Molecule
摘要： Ultrafast XUV-chemistry is offering new opportunities to decipher the complex dynamics taking place in highly excited molecular states and thus better understand fundamental natural phenomena as molecule formation in interstellar media. We used ultrashort XUV light pulses to perform XUV-pump–IR-probe experiments in caffeine as a model of prebiotic molecule. We observed a 40-fs decay of excited cationic states. Guided by quantum calculations, this timescale is interpreted in terms of a non-adiabatic cascade through a large number of highly correlated states. This shows that the correlation driven non-adiabatic relaxation seems to be a general process for highly excited states, which might impact our understanding of molecular processing in interstellar media.
关键词： non-adiabatic cascade,quantum calculations,Ultrafast XUV-chemistry,interstellar media,caffeine
更新于2025-09-09 09:28:46