Highly efficient Non-Fullerene Organic Solar Cell with Fine Tuned Hole Transporting Layer

Non-fullerene organic solar cells have experienced rapid development in the past few years with their impressive optoelectronic properties and great potential in practical applications. Here, we present a facile and effective strategy to improve the device performance through hole-transporting layer (HTL) modification. By optimizing Wox (nanoparticles): PEDOT:PSS composition, the surface free energy of the HTL is improved, hence influences the crystallization mechanism of PBDB-TF:IT4F bulk-heterojunction (BHJ) active layer. In-situ grazing incident X-ray diffraction (GIXD) is applied to monitor the crystallization kinetics and morphology formation of the active layer based on different HTLs. The crystal coherence lengths and lamellar stacking distance as well as the phase separation are adjusted by various HTLs. In addition, the optimized HTL can promote more balanced carrier transport ability, leading to reduced non-radiative recombination and higher fill factor. The crystallization to structure, and film property to device performance relationship are established. A power conversion efficiency of 14.2% is achieved based on laboratorial spin-coating process, while an efficiency of 11.9% is obtained via industrial comparable slot-die printing fabrication.