Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV23)
Publication date: 30th March 2023
Halide perovskite semiconductors have captured significant research attention for application in optoelectronic devices, in particular solar cells, due to their outstanding properties and straightforward material synthesis. Amongst these favourable properties, the seemingly “slow” cooling of hot (nonequilibrium, high energy) carriers—which distinguishes halide perovskites as candidate materials for the light-absorbing layer in hot carrier solar architectures—is the subject of an increasing share of the community’s focus [1, 2]. The dynamics of hot carriers are commonly studied experimentally via transient absorption spectroscopy (TA), which allows for observation of the cooling of hot carriers following photoexcitation by an ultrashort laser pulse, and the advanced two-dimensional electronic spectroscopy technique (2DES), which can resolve shorter timescales and, thus, additionally enables scrutiny of carrier thermalization [3, 4]. These techniques are powerful, but there is generally a limit to the strength of the conclusions that can be drawn concerning the physical processes underlying the carrier dynamics in the probed material by virtue of these experimental measurements alone. Consequently, the origin of observations of long hot carrier cooling times in halide perovskite materials remains debated, despite the increase in traction of the “hot phonon bottleneck” hypothesis. Here, we present semiclassical simulation of semiconductor charge carrier dynamics—using the ensemble Monte Carlo method to solve the Boltzmann transport equation for non-equilibrium carrier distributions—as a valuable partner to experiment in elucidating the transient carrier dynamics in halide perovskites and other semiconductors [5]. We include results from such simulations and draw qualitative inferences about the carrier dynamics in halide perovskites, also highlighting the care that must be taken in analysing TA experiments. We discuss remaining challenges and opportunities to develop our approach to allow experimental measurements to be reproduced.