Microstructural and optical properties of HC(NH2)2PbI3 thin films prepared by single source thermal evaporation

The HC(NH 2 ) 2 PbI 3 thin films as the perovskite solar cells absorption layer were prepared by single-source thermal evaporation. The stoichiometric ratio effects of HC(NH 2 ) 2 I/PbI 2 precursors on the properties of HC(NH 2 ) 2 PbI 3 thin films were investigated. The microstructure, surface morphology and optical properties of HC(NH 2 ) 2 PbI 3 thin films were characterized by X-ray diffraction (XRD), energy dispersive spectroscope, scanning electron microscopy and spectrophotometer respectively. The results show that, with stoichiometric ratio of FAI/PbI 2 3:1, the XRD results of formamidine lead iodine thin films prepared by single source thermal evaporation indicated the typical peaks of HC(NH 2 ) 2 PbI 3 thin films with few impurities. The dense and uniform films were formed with large crystal grains on the surface and high crystallization. The Pb/I element ratio was approximate to the ideal stoichiometric ratio of HC(NH 2 ) 2 PbI 3 thin films. The band gap of the HC(NH 2 ) 2 PbI 3 thin film calculated was 1.5 eV, which satisfied the optical properties requirement of absorbers for perovskite solar cell applications, making them potential applicable for large-area efficient perovskite solar cells.