Improved Performance of Perovskite Light-Emitting Diodes by Dual Passivation with an Ionic Additive

Metal halide perovskites are considered to be the new generation of semiconductors for optoelectronic devices because of their low material cost and superior optical and electrical properties, such as narrow emission line width, tunable emission wavelength, and high charge carrier mobility. However, the morphological and energetic defects of perovskites grown from solution casting hinder the maximum achievable performance of devices. Additive strategy has been demonstrated as a facile and effective method to acquire high quality perovskite films. In this work, we introduce three ionic additives, namely, tetrabutylammonium bromide (TBABr), benzyltriethylammonium bromide (BTEABr), and benzyltributylammonium bromide (BTBABr), into CH3NH3Br3 (MAPbBr3) precursor solution, respectively, to prepare pinhole-free perovskite films with reduced defect density. Perovskite light-emitting diodes (PeLEDs) incorporating BTBABr-modified MAPbBr3 emitter exhibits a significantly reduced turn-on voltage from 4.6 to 2.6 V and improved maximum luminance and current efficiency of 23646 cd/m2 and 3.39 cd/A compared with those of 3926 cd/m2 and 0.27 cd/A of pristine MAPbBr3-based device.