Post-Treatment Free Yttrium Phosphotungstate Anode Interfacial Material for Organic Solar Cells with 20.55% Efficiency

Hole transport layers (HTLs) play a crucial role in organic solar cells, yet achieving high performance while maintaining simple processing requirements remains challenging. Here, we report a facile strategy utilizing yttrium-doped phosphotungstate (YPWO) as an efficient HTL material, prepared through a straightforward solution process without requiring post-treatment. The incorporation of yttrium enhances molecular stacking and reduces defect states, resulting in improved charge transport properties and suppressed recombination losses. YPWO-based devices achieve a power conversion efficiency (PCE) of 20.55% (certified efficiency of 20.30%), attributed to optimized energy level alignment, reduced trap states, and improved charge carrier mobility. Additionally, YPWO demonstrates thickness tolerance and compatibility across various photovoltaic systems, achieving PCEs exceeding 19% with different photoactive layers. This work presents a viable strategy for developing efficient HTL materials, offering a practical pathway toward commercially viable organic solar cells through simplified processing.