Unravelling free carrier and exciton dynamics in hybrid organic-inorganic perovskites using transient absorption spectroscopy

Mixed-cation lead mixed-halide perovskites have been shown to good photostability, thermal stability and high power conversion efficiency, proving to be good candidates as energy harvesting materials [1]. Transient absorption spectroscopy is a powerful tool to study the response of free carriers and excitons upon photoexcitation in the perovskites [2]. Here, we excite FA_0.85 Cs_0.15 PbI_2.9 Br_0.1 thin films with bandgap and above-bandgap pump pulses, and probe the sample with white light. Our results show that, compared to resonant excitation, shorter-wavelength excitation generates more free carriers, and by increasing the pump fluence, bandgap renormalization and hot-phonon bottleneck can be achieved.


[1] Science, 351, 151-155 (2016)
[2] Nat. Photonics, 10, 53 (2016)