Communicating Two States in Perovskite Revealed by Time-Resolved Photoluminescence Spectroscopy

Abstract

Organic-inorganic perovskite as a promising candidate for solar energy harvesting has attracted immense interest for its low-cost preparation and extremely high quantum efficiency. However, the fundamental understanding of the photophysics in perovskite remains elusive. In this work, we have revealed two distinct states in MAPbI3 thin films at low temperature through time-resolved photoluminescence spectroscopy (TRPL). In particular, we observed a photo-induced carrier injection from the high energy (HE) state to the low energy (LE) state which has a longer lifetime. The strong interaction between the two states, evidenced by the injection kinetics, can be sensitively controlled through the excitation power. Understanding of the interacting two-states not only sheds light on the long PL lifetime in perovskite but also helps to understand the different behavior of perovskite in response to different excitation power. Further efforts in modifying the low energy state could significantly improve the quantum efficiency and lead to novel application in optoelectronics based on perovskite.

Direct conversion X-ray detectors with 70 pA cm−2 dark currents coated from an alcohol-based perovskite ink

“…2a). These features have been previously observed in lead halide perovskite films [24][25][26][27][28][29] and are variously ascribed to Rashba splitting effects, [28][29][30] the tetragonal-toorthorhombic phase transition, 27 and emission from surface vs. bulk states in the crystal. 25,26 Given the prevalence of large, micron-sized grains in the blade-coated film (Fig.…”

Thermally Assisted Rashba Splitting and Circular Photogalvanic Effect in Aqueously Synthesized 2D Dion–Jacobson Perovskite Crystals

“…The instability of momentum-indirect excitons might lead to the generation of free carriers in addition to excitons, resulting in a nonlinear excitonic emission under nonresonant optical pumping. 43 In addition, the carrier injection from high-energy to low-energy indirect valleys 44 might also affect the k value. Nevertheless, future experimental efforts are required to unambiguously clarify this, which are beyond the scope of the present work.…”

Deciphering the effect of traps on electronic charge transport properties of methylammonium lead tribromide perovskite

“…These energy states affect the relaxation dynamics of free carriers by trapping processes and therefore, detrimentally influence the free charge transport properties such as lifetime and drift mobility. The detection and characterization of such traps and their associated relaxation dynamics are highly challenging due to the dominant non-radiative nature of such energy transitions in any types of semiconductors, restraining their investigation by photoluminescence spectroscopies [29][30][31] . Other techniques such as thermal emission is limited by the low activation energy of shallow levels and the presence of several phase transitions in OMHPs [32,33] preventing them from adequate cooling to reveal the trapping parameters of defects.…”