Vacuum-Assisted Blade Coating MAPbI3 Homojunction Thick Film for Highly Sensitive X-Ray Detectors

Abstract

Large-area perovskite (PVK) X-ray detectors exhibit significant potential for commercial applications. However, the production of uniform and dense thick films as well as achieving efficient carrier transport over tens of microns in thick PVK films, remain major challenges for highly sensitive X-ray detection. Herein, an innovative vacuum-assisted blade coating strategy is proposed using PVK inks that strictly controls the nucleation and growth of PVKs to prepare large-area, high-quality MAPbI₃ homojunction thick films. Arising from the formation of a type II homojunction between the top and bottom PVK layers, and effective reduction of the density of defect states, the resultant homojunction film exhibits impressive performances, including an increase in carrier lifetime from 1272 to 9335 ps, an increase in surface photovoltage change from 93 to 386 mV, and nearly three times higher carrier mobility-lifetime product compared with pristine NMP-PVK film. Consequently, the X-ray detector based on homojunction film demonstrates a high sensitivity of 1.3 × 10⁵ µC Gy_air⁻¹ cm⁻², surpassing the most previously reported values for X-ray detector using blade coating method. This research provides a convenient approach for preparing large-area PVK thick films and establishes a solid foundation for the development of X-ray detection.