Dynamical co-existence of excitons and free carriers in perovskite probed by density-resolved fluorescent spectroscopic method

Abstract

Using transient fluorescent spectra at time-zero, we develop a density-resolved fluorescent spectroscopic method for investigating photoproducts in CH3NH3PbI3 perovskite and related photophysics. The density dependent dynamical co-existence of excitons and free carriers over a wide density range is experimentally observed for the first time. The exciton binding energy (EB) and the effective mass of electron-hole pair can be estimated based on such co-existence. No ionic polarization is found contributing to photophysical behavior. It also solves the conflict between the large experimentally measured EB and the small predicted values. The spectroscopic method also helps to detect the true free carrier density under continuous illumination without the interference of ionic conductivity. Our methods and results profoundly enrich the study and understanding of the photophysics in perovskite materials for photovoltaic applications.

arXiv comment15 pages for manuscript, 4 figures, original paper 7 pages for supplemental materials, 3 figures, 2 tables

References in corpus (4)

• Atomistic origins of high-performance in hybrid halide perovskite solar cells
• Direct Measurement of the Exciton Binding Energy and Effective Masses for Charge carriers in an Organic-Inorganic Tri-halide Perovskite
• Revealing the role of organic cations in hybrid halide perovskites CH3NH3PbI3
• Role of Polar Phonons in the Photo Excited State of Metal Halide Perovskites

Cited by in corpus (2)

• Temperature-dependent optical spectra of single-crystal (CH${}_3$NH${}_3$)PbBr${}_3$ cleaved in ultrahigh vacuum
• Revealing two heat-annealing related photoproduct systems and widely existed subgrain domains in organolead perovskite