TRMC as Technique to Evaluate the Radiation Hardness of Perovskite Film Passivation

The influence of high-energy proton irradiation on the charge carrier kinetics in triple cation, triple halide semiconducting perovskite films with applications in medical instrumentation and space photovoltaics (PV) has been investigated with the contactless time-resolved microwave conductivity (TRMC) measurement technique. In the first experiment, the high sensitivity of the measurement setup for the characterization of the silicon solar cell degradation under the same optical excitation conditions has been demonstrated. Regarding the excess charge carrier kinetics after pulsed excitation in perovskite films, it is found that the TRMC transients do not follow a single exponential decay. In contrast to the results on crystalline silicon, only minor changes in the charge carrier decay are observed in these perovskite films after proton irradiation. It has also been shown that the technique can be used to check for the efficient surface passivation of the perovskite films with phenethyl ammonium iodide (PEAI) layers. The stability of this passivation under irradiation has been investigated and a more pronounced change in the decay time is found for the passivated films when compared to the nonpassivated film. The results of this TRMC measurement have been compared to the properties of solar cells, using the same substrates and thin-film layers as absorption layers. A good correlation between the transient measurements with the external quantum efficiency (EQE) spectra, obtained from the solar cell characterization, has been found.