Screening and Synthesis of Metal Phosphides as Novel Materials for Thin-Film Solar Absorbers

As the adoption of solar increases worldwide, there is interest in thin-film solar absorbers that require less energy to manufacture, are low cost, and are operationally stable. Using a high-throughput screening of metal pnictides in the Materials Project Database, we've identified candidate thin-film solar absorbers with optimal band gaps, long carrier lifetimes, defect tolerance, and high stability. This work will focus on MgP4, a binary polyphosphide void of critical or expensive elements and with calculated indirect and direct band gaps of 1.25 eV and 1.35 eV, respectively. We have synthesized both bulk powders and single crystals of MgP4 with an experimental band gap of 1.31 eV and high stability. The use of abundant, inexpensive elements and a band gap of 1.31 eV, makes MgP4 a promising candidate as a solar absorber in a single junction thin-film solar cell. This work highlights the potential of exploring MgP4 and the numerous other known metal polyphosphides as solar absorbers.