A molecular interaction-diffusion framework for predicting organic solar cell stability.

Masoud Ghasemi, Nrup Balar, Zhengxing Peng, Huawei Hu, Yunpeng Qin, Taesoo Kim, Jeromy J Rech, Matthew Bidwell, Walker Mask, Iain McCulloch, Wei You, Aram Amassian, Chad Risko, Brendan T O'Connor, Harald Ade

Research output: Contribution to journalArticlepeer-review

262 Scopus citations

Abstract

Rapid increase in the power conversion efficiency of organic solar cells (OSCs) has been achieved with the development of non-fullerene small-molecule acceptors (NF-SMAs). Although the morphological stability of these NF-SMA devices critically affects their intrinsic lifetime, their fundamental intermolecular interactions and how they govern property-function relations and morphological stability of OSCs remain elusive. Here, we discover that the diffusion of an NF-SMA into the donor polymer exhibits Arrhenius behaviour and that the activation energy E$_{a}$ scales linearly with the enthalpic interaction parameters χ$_{H}$ between the polymer and the NF-SMA. Consequently, the thermodynamically most unstable, hypo-miscible systems (high χ) are the most kinetically stabilized. We relate the differences in E$_{a}$ to measured and selectively simulated molecular self-interaction properties of the constituent materials and develop quantitative property-function relations that link thermal and mechanical characteristics of the NF-SMA and polymer to predict relative diffusion properties and thus morphological stability.
Original languageEnglish (US)
JournalNature materials
DOIs
StatePublished - Jan 12 2021

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