Electron-Beam Irradiation Induced Regulation of Surface Defects in Lead Halide Perovskite Thin Films

Organic-inorganic hybrid perovskites(OIHPs)have been intensively studied due to their fascinating optoelectronic performance.Electron microscopy and related characterization techniques are powerful to figure out their structure-property relationships at the nanoscale.However,electron beam irradiation usually causes damage to these beam-sensitive materials and thus deteriorates the associated devices.Taking a widely used CH_(3)NH_(3)PbI_(3)film as an example,here,we carry out a comprehensive study on how electron beam irradiation affects its properties.Interestingly,our results reveal that photoluminescence(PL)intensity of the film can be significantly improved along with blue-shift of emission peak at a specific electron beam dose interval.This improvement stems from the reduction of trap density at the CH_(3)NH_(3)PbI_(3)surface.The knock-on effect helps expose a fresh surface assisted by the surface defect-induced lowering of displacement threshold energy.Meanwhile,the radiolysis process consistently degrades the crystal structure and weaken the PL emission with the increase of electron beam dose.Consequently,the final PL emission comes from a balance between knock-on and radiolysis effects.Taking advantage of the defect regulation,we successfully demonstrate a patterned CH_(3)NH_(3)PbI_(3)film with controllable PL emission and a photodetector with enhanced photocurrent.This work will trigger the application of electron beam irradiation as a powerful tool for perovskite materials processing in micro-LEDs and other optoelectronic applications.