High-quality blade-coated CH3NH3PbI3 perovskite thick films for high-performance X-ray detection

Abstract

A perovskite CH₃NH₃PbI₃ (MAPbI₃) polycrystalline thick film has outstanding advantages in large-area flat-panel X-ray imaging applications compared with its single crystal (SC) and polycrystalline wafer counterparts. At present, the improved blade coating technique combined with the in situ grain-growth induced pore-filling method is an effective way to fabricate high-quality MAPbI₃ polycrystalline thick films. However, the paste used for the improved blade coating technology is prepared by mixing the solvent with synthesized MAPbI₃ microcrystalline powders, which has poor crystal quality. If their crystal quality can be improved, the optoelectronic performance of blade-coated MAPbI₃ thick films should be further enhanced. In this work, MAPbI₃ microcrystalline powders with high crystal quality produced by grinding MAPbI₃ SCs serve as the powders in the paste for the improved blade-coating technique. Dense MAPbI₃ thick films are obtained. The X-ray detector with a ITO/MAPbI₃ thick film/carbon electrode structure shows a low dark current drift of 7.72 × 10⁻⁷ nA cm⁻¹ s⁻¹ V⁻¹, a large μτ product of 2.49 × 10⁻³ cm² V⁻¹, a high sensitivity of 2751.25 μC Gy⁻¹ cm⁻², a low detection limit of 15.1 nGy s⁻¹, and good long-term operational stability, thus achieving a high-quality X-ray image. This study provides an effective strategy to achieve high-quality MAPbI₃ thick films through manipulating the crystal quality of MAPbI₃ powder for high-performance X-ray detection.