A Dopant‐Free Hole Transporting Layer for Efficient and Stable Planar Perovskite Solar Cells

Abstract

Herein, a new dopant‐free organic material, PV2000, as a stable hole transporting layer (HTL) for the fabrication of stable and efficient perovskite solar cells (PSCs) is introduced. For this purpose, planar PSCs using a triple‐A cation perovskite composition are fabricated and the commonly used 2,2′,7,7′‐tetrakis[N,N‐di(4‐methoxyphenyl)amino]‐9,9′‐spirobifluorene (spiro‐OMeTAD) HTL is replaced by dopant‐free PV2000 polymer. The characterization results disclose that the PV2000 has a great thermal stability, good hole mobility, and suitable band alignment that matches well with the valence band of triple‐A cation perovskite. After proper optimization of PV2000 film thickness, a planar PSC with maximum power conversion efficiency (PCE) of 18.93% is achieved, which is comparable with the spiro‐based device (19.62%). Moreover, the PCE of the PV2000‐based device is further improved up to 20.5% using a band alignment engineering by deposition of thin layer of polyvinylpyrrolidone (PVP) at perovskite/HTL interface. More importantly, it is found that the thermal, moisture, and operational stabilities of the PSCs with PV2000 HTL are improved drastically compared with the spiro‐based devices, where the PSC with PV2000 retains ≈88% of its initial PCE value under continuous illumination for 250 h compared with the spiro‐based one (39%).