| 초록 |
Despite the recent dramatic improvement in the power conversion efficiencies (PCEs) of organic solar cells (OSCs) over 18%, the underlying mechanism of high device performance remain controversial. In this work, we investigated the origin of high performance in PM6:Y6 OSCs by performing a comprehensive analysis based on transient optoelectronic measurements. Compared with other non-fullerene photovoltaic blends, PM6:Y6 shows lower energetic disorder, in which low density of intra-bandgap tail states presents energetically narrow distribution. As a result, charge trapping into these trap states concomitant with losses in quasi-Fermi level splitting is largely suppressed, enabling near-ideal recombination kinetics under operational conditions. Through the density function theory (DFT) calculation, we propose the low energetic disorder in the PM6:Y6 system could be ascribed to the rigid molecular conformation of the Y6 acceptor. |
