Optimizing Perovskite Solar Cell Stability Through Automated, Multimodal and Non-Contact Characterization

Metal halide perovskites are a promising photovoltaic technology with power conversion efficiencies that rival commercial technologies. However, current devices suffer from poor stability, durability, and reliability. Currently, the entire community is trying to identify the perovskite formulations, additives, charge transport layers, and encapsulation strategies that may enable decade module lifetimes. The parameter space is large and therefore requires accelerated learning cycles to rapidly identify the optimal material sets. In particular, it has been challenging to develop accelerated testing protocols that are predictive of field performance and give insights into sources of degradation. In order to overcome this challenge, we have developed and built an automated, multi-modal characterization tool that can perform material and device stability testing under various environmental conditions and illumination intensities. This tool is unique in that after various stress tests it can automatically perform several important measurements such as in-situ time-resolved photoluminescence (PL), spectrally resolved PL, transmission, and Raman spectroscopy to enable root-cause analysis of degradation modes. We use the tool to study the stability of ~100 perovskite samples prepared with different ink chemistries, passivation layers, and encapsulants. With this large data set, we are able to perform higher dimensional data analysis (i.e. machine learning) to identify the key material parameters and correlate them with material degradation rates under continuous illumination. This work provides a deeper mechanistic understanding of perovskite device stability and the key optoelectronic signatures that track with reductions in stability. The tool is capable of generating previously inaccessible large data sets that are required to optimize perovskite stability and supports root-cause analysis of traditional ISOS and IEC protocols.