Efficient and stable perovskite solar cells using the tungsten trioxide as an interfacial passivation layer

In this paper, the tungsten trioxide (WO3) was used as an interfacial layer between mesoporous TiO2 and perovskite film to suppress grain boundaries of the hole transport layer-free PSCs. With this treatment approach, perovskite film was fabricated with dense and uniform morphology with suppressed charge recombination. Meanwhile, the untreated PSC suffers from severe recombination process, which let to decline the performance of the fabricated device. The UV-vis absorption spectrum of the perovskite with WO3 treatment showed an improved photoelectric performance compared with that of untreated perovskite. The optimized PSCs with WO3/ TiO2 bilayer yield a PCE of 14.7% (0.08 cm2 active area) and have long-term ambient stability (30 days). The overall results confirmed that the WO3-coated TiO2-based electron transport layers (ETL) has a positive effect on the photovoltaic performance of the solid state PSCs.