The work collaborating with the H. Dai and B. J. Hwang groups just got published in J. Mater. Chem.
Abstract: Organolead halide perovskites are an impressive and relatively recent class of light-absorbing materials for solar cells and light-emitting devices. It has been reported that exposure of the perovskites materials to light has negative impacts on device performance. Also, surface recombination has been reported as a major obstacle to the total carrier lifetime in perovskite polycrystalline thin films. Herein, we explored the role played by Nanosecond pulsed UV laser-irradiation on carrier dynamics in perovskites thin films. Steady-state and time-resolved photoluminescence measurements revealed the interplay of disorder and heterogeneity on photoexcited carrier dynamics, while in-situ micro Raman and Angle dispersive X-ray diffraction showed the mechanisms of crystal phase reconstruction. Exposures to laser light leads to rapid crystal phase reconstruction and hence, unexpectedly, extend PL lifetime by fourfold instead of promoting degradation. This verifies nanosecond pulsed laser irradiation plays a beneficial role in improving in optoelectronic material parameters. Our findings reveal that pulsed laser irradiation is a new approach to the reconstruction of microstructure and offers beneficial effects in the manufacture of perovskites solar cells. Moreover, this work provides a clear insight towards identifying the physical origin behind the disorder, heterogeneity, film reconstruction and nano-structuring as well as their correlation with improved PL lifetime.
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