Prolonging exciton diffusion length via manipulating molecular stacking enables pseudo-planar heterojunction organic solar cells over 19% efficiency
【Abstract】
The limited exciton diffusion length (LD) of organic semiconductors constraints exciton dissociation in pseudo-planar heterojunction (PPHJ) organic solar cells (OSCs), which is deemed as the bottleneck issue hampering the further improvement in power conversion efficiencies (PCEs). Herein, the solid-additive strategy is proposed to efficiently prolong LD in PPHJ OSCs via developing a volatile solid additive, SA-5F and blending it into non-fullerene acceptors. The addition of SA-5F endows the Y6+ film with improved crystallinity and more compact molecular stacking for higher photoluminescence quantum yield, larger overlap between absorption and emission spectra, and shorter intermolecular distance, compared with the Y6 pristine film. Thus, the Y6+ film achieves a higher exciton diffusion coefficient of 1.36 × 10-3 cm2 s-1 and thus ~24% improvement in LD to 10.27 nm. The prolonged LD enables D18/Y6+ based PPHJ devices to gain more efficient exciton dissociation and weaker charge recombination, compared with D18/Y6 counterparts. Therefore, D18/Y6+ based PPHJ OSCs afford an impressive PCE of 19.11%, which is among the highest values. Moreover, this strategy exhibits excellent universality in improving photovoltaic performance for different systems. It demonstrates that introducing solid additive is an efficient and universal strategy to prolong the LD in PPHJ OSCs and thus boost PCEs.
【Author】
Wang Ke, Fuwen Zhao, Yufan Zhu, Yi He, Zesheng Liu, Xiao Han, Qi Ai, Xingxing Shen, Bao Li, Jianqi Zhang, Yuze Lin, Chun-Ru Wang, Dan He
【Journal】
Journal of Materials Chemistry A(IF：10.7) Time：2024-04-16
