@article{Seo2024, 
author = {Soodeok Seo and Jun-Young Park and Jin Su Park and Seungjin Lee and Do-Yeong Choi and Yun-Hi Kim and Bumjoon J. Kim},
title = {Polymer donors with hydrophilic side-chains enabling efficient and thermally-stable polymer solar cells by non-halogenated solvent processing},
year = {2024},
journal = {Nano Research Energy},
volume = {3},
pages = {e9120088},
keywords = {polymer solar cell, polymer donor, OEG side-chain, non-halogenated solvent process, side-chain engineering},
url = {https://www.sciopen.com/article/10.26599/NRE.2023.9120088},
doi = {10.26599/NRE.2023.9120088},
abstract = {Polymer solar cells (PSCs) with high power conversion efficiency (PCE) and environment-friendly fabrication are the main requirements enabling their production in industrial scale. While the use of non-halogenated solvent processing is inevitable for the PSC fabrication, it significantly reduces the processability of polymer donors (PDS) and small-molecule acceptors (SMAs). This often results in unoptimized blend morphology and limits the device performance. To address this issue, hydrophilic oligoethylene glycol (OEG) side-chains are introduced into a PD (2EG) to enhance the molecular compatibility between the PD and L8-BO SMA. The 2EG PD induces higher crystallinity and alleviates phase separation with the SMA compared to the reference PD (PM7) with hydrocarbon side-chains. Consequently, the 2EG-based PSCs exhibit a higher PCE (15.8%) than the PM7-based PSCs (PCE = 14.4%) in the ortho-xylene based processing. Importantly, benefitted from the reduced phase separation and increased crystallinity of 2EG PDS, the 2EG-based PSCs show enhanced thermal stability (84% of initial PCE after 120 h heating) compared to that of the PM7-based PSCs (60% of initial PCE after 120 h heating). This study demonstrates the potential of OEG side-chain-incorporated materials in developing efficient, stable, and eco-friendly PSCs.}
}