Type-i heterostructure and improved phase stability of formamidinium lead iodide perovskite grown on WS₂

Heterostructures of two-dimensional materials provide an opportunity for the discovery of novel properties and improved material performances. In this work, we demonstrate the chemical vapor deposition growth of two-dimensional perovskite/WS₂ heterostructures. Owing to type-I band alignment, photoluminescence (PL) measurements indicated the photogenerated carrier transfer from the WS₂ to the perovskite layer. In order to investigate the carrier transfer mechanism, power-dependent PL spectra were measured. The PL intensity of the two-dimensional perovskite grown on WS₂ exhibited super-linear dependence to the excitation power. In addition, twodimensional perovskites grown on WS₂ showed better air stability compared with the pristine perovskite. The improved stability is attributed to strain in the two-dimensional perovskite layer induced by the underlying WS₂. The results presented here offer better understanding of the twodimensional perovskite based heterostructures and their potential use in practical applications, such as light emitting diodes and lasers.