Careful interpretation of time-resolved photoluminescence (TRPL) measurements can substantially improve our understanding of the complex nature of charge-carrier processes in metal-halide perovskites, including, for instance, charge separation, trapping, and surface and bulk recombination. In this work, we demonstrate that TRPL measurements combined with powerful analytical models and additional supporting experiments can reveal insights into the charge-carrier dynamics that go beyond the determination of minority-charge-carrier lifetimes. While taking into account doping and photon recycling in the absorber layer, we investigate surface and bulk recombination (trap-assisted, radiative, and Auger) by means of the shape of photoluminescence transients. The observed long effective lifetime indicates high material purity and good passivation of perovskite surfaces with exceptionally low surface recombination velocities on the order of about 10 cm=s. Finally, we show how to predict the potential open-circuit voltage for a device with ideal contacts based on the transient and steady-state photoluminescence data from a perovskite absorber film and including the effect of photon recycling.

Photon recycling has been recently shown to be measurable in perovskite solar cells. Here we discuss the impact of this effect on the open-circuit voltage of perovskite solar cells and show how the voltage boost due to photon recycling depends on electronic properties, such as Shockley–​Read–​Hall lifetimes, and on the optical properties of the device, such as the amount of parasitic absorption and the efficiency of light outcoupling.

The transient photoluminescence of CH3NH3PbI3/PC61BM heterojunctions is simulated numerically allowing the extraction of the interfacial recombination velocity of experimentally measured samples.

Photon recycling is a fundamental physical process that becomes especially important for photovoltaic devices that operate close to the radiative limit. This implies that the externally measured radiative decay rate deviates from the internal radiative recombination rate of the material. In the present Letter, the probability of photon recycling in organic lead halide perovskite films is manipulated by modifying the underlying layer stacks. We observe recombination kinetics by time-resolved photoluminescence that is controlled by the optical design of the chosen layer structure. Quantitative simulations of decay rates and emission spectra show excellent agreement with experimental results if we assume that the internal bimolecular recombination coefficient is ∼66% radiative.

Recent evidence for bimolecular nonradiative recombination in lead-halide perovskites poses the question for a mechanistic origin of such a recombination term. A possible mechanism is Auger recombination involving two free charge carriers and a trapped charge-carrier. To study the influence of trap-assisted Auger recombination on bimolecular recombination in lead-halide perovskites, we combine estimates of the transition rates with a detailed balance compatible approach of calculating the occupation statistics of defect levels using a similar approach as for the well-known Shockley–Read–Hall recombination statistics. We find that the kinetics resulting from trap-assisted Auger recombination encompasses three different regimes: low injection, high injection, and saturation. Although the saturation regime with a recombination rate proportional to the square of free carrier concentration might explain the nonradiative bimolecular recombination in general, we show that the necessary trap density is higher than reported. Thus, we conclude that Auger recombination via traps is most likely not the explanation for the observed nonradiative bimolecular recombination in CH 3 NH 3 PbI 3 and related materials.