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a??Double-Acceptor-Typea?? Random Conjugated Terpolymer Donors for Additive-Free Non-Fullerene Organic Solar Cells
摘要： Random conjugated terpolymers (RCTs) not only promote great comprehension and realization for state-of-the-art high effective non-fullerene polymer solar cells (OSCs) but also offer a simple and practical synthetic strategy. However, the photovoltaic properties of RCTs yet lagged behind that of the donor-acceptor alternating copolymer, especially in the additive-free devices. Hence, we developed two feasible “double acceptor type” random conjugated terpolymers, PBDB-TAZ20 and PBDB-TAZ40. The additive-free OSCs based on PBDB-TAZ20:ITIC and PBDB-TAZ40:ITIC exhibit decent efficiencies of 12.34% and 11.27%, respectively, which both surpass the PBDB-T:ITIC-based device. For the RCTs, the reasonably weakened crystallinity and reduced phase separation degree are demonstrated to help improve charge transport, reduce bimolecular recombination and thus enhance the photovoltaic performance of the additive-free OSCs. The results imply that adding a third moiety into the D-A polymer donors provides a simple but efficient synthetic approach for high-performance OSCs.
关键词： polymer solar cells,crystallinity,non-fullerenes,morphology,random terpolymers
更新于2025-09-23 15:19:57
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Overcoming the Limitations of Transient Photovoltage Measurements for Studying Recombination in Organic Solar Cells
摘要： Transient photovoltage (TPV) measurements are frequently used to study recombination processes in thin-film solar cells by probing the decay of a small optically-induced voltage perturbation to infer the charge carrier dynamics of devices at open circuit. However, the validity of this method to probe organic semiconductors has recently come into doubt due to large discrepancies in reported carrier lifetime values for the same systems, and the reporting of unrealistic reaction order values. In this work, we explore the validity of TPV to extract reliable charge carrier lifetimes in thin-film solar cells through the use of time-dependent drift diffusion simulations and measurements. We find that in low mobility materials, TPV serves primarily as a probe of charge carrier redistribution in the bulk rather than bulk recombination dynamics, and that the extracted time constant is highly mobility dependent. To address this shortcoming, we develop Transient Photo-Charge (TPQ) a new technique to measure the charge carrier density during the photo-voltage decay and apply it to study the recombination dynamics in a series of (fullerene and non-fullerene) organic solar cell systems. We show that using this technique the charge carrier recombination lifetime in the active layer can be more accurately determined.
关键词： Characterization Tools,organic solar cells,Thin Films,non-fullerenes acceptor
更新于2025-09-16 10:30:52