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Abstract
The study of the photophysical properties of organic-metallic lead halide perovskites,
which demonstrate excellent photovoltaic performance in devices with electron- and
hole-accepting layers, helps to understand their charge photogeneration and recombination
mechanism and unravels their potential for other optoelectronic applications. We report
surprisingly high photoluminescence (PL) quantum efficiencies, up to 70%, in these
solution-processed crystalline films. We find that photoexcitation in the pristine
CH3NH3PbI3-xClx perovskite results in free charge carrier formation within 1 ps and
that these free charge carriers undergo bimolecular recombination on time scales of
10s to 100s of ns. To exemplify the high luminescence yield of the CH3NH3PbI3-xClx
perovskite, we construct and demonstrate the operation of an optically pumped vertical
cavity laser comprising a layer of perovskite between a dielectric mirror and evaporated
gold top mirrors. These long carrier lifetimes together with exceptionally high luminescence
yield are unprecedented in such simply prepared inorganic semiconductors, and we note
that these properties are ideally suited for photovoltaic diode operation.