High-Throughput Computational Discovery of Long Carrier Lifetime and Stable New Solar Absorbers

Thin-film photovoltaic technology has advantages to silicon in terms of flexibility, lower manufacturing energy needs, and use in tandem cells. However, the high-efficiency thin-film technologies available (e.g., CIGS, CdTe or halide perovskites) have issues in terms of cost, element abundance, or long-term stability. Finding new solar absorbers is a slow process involving complex experimental synthesis and characterization. First-principles computations on the other hand offer an attractive way to speed up this process. Here, we will report on a large-scale high-throughput computational search for new solar absorbers among known inorganic materials. Importantly, the need for high carrier lifetime is taken into account by including in the screening intrinsic defects and their role as potential Shockley-Read-Hall recombination centers. Screening ~40,000 known inorganic compounds, we identify a handful of promising new solar absorbers. I will discuss the chemistries that we identified and highlight a few interesting candidates. I will especially focus on BaCd2P2, a Zintl phosphide where our follow-up experiments confirm the promising properties including a ~1.5 eV direct band gap but also bright band-edge photoluminescence, long carrier lifetime, and high stability. Beyond BaCd2P2, our work highlights the discovery of an entire family of AM2P2 Zintl phosphides with our recent exciting results on CaZn2P2 thin films.