Homogeneous bulk heterojunction domains with continuous charge pathway via hydrophobic membrane filtration for stable photo and dark current operations

Abstract

Polymer donor PM6 (PBDB-T-4F) has attracted significant attention in optoelectronics. However, PM6 suffers from solubility issues owing to its molecular weight and solvent and environmental conditions. These properties cause the formation of inhomogeneous domains within the active layer, resulting in morphological degradation and low device reproducibility. Herein, we fabricate a highly uniform polymer-donor-based bulk heterojunction (BHJ) active layer by pre-treating the BHJ solution via hydrophobic filtration. Because of the filtration step, the BHJ active layer exhibited decreased leakage current, accelerated charge transport, and other enhanced physicochemical properties. Correspondingly, optoelectronics with such improved properties exhibit high performance under various illumination conditions. Specifically, the linear dynamic range of the filtered BHJ-based device is wider than that of a non-filtered BHJ-based device under various voltage biases. Moreover, the power conversion efficiency of the device at mid-low illumination (6.5 klux) improves upon filtration, increasing from 15.73% to 20.96%. This study contributes to the development of light-harvesting devices and detectors, providing insights into stable and reproducible organic optoelectronics.