1, Lawrence Berkeley National Lab, Berkeley, California, United States
3, National Renewable Energy Laboratory, Golden, Colorado, United States
4, University of California, Berkeley, Berkeley, California, United States
Given rapid advances in photovoltaics, transparent electronics, and other emerging energy technologies, the development of p-type transparent conductors (TCs) has been a relatively slow-moving front. Both n-type and p-type TCs are conventionally oxides, but there is increasing evidence that chalcogenide (S, Se, Te) semiconductors should have higher hole transport and probability of p-type doping than oxides (in exchange for lower transparency). We use a high throughput computational framework to screen a large database of chalcogenide compounds likely to have a high hole conductivity and high optical transparency. Our ultimate goal is to synthesize promising compounds in the laboratory for use in stable devices. To this effect, we investigate potential metrics for TC performance including various weighting methods for Boltzmann transport calculations, defect formation energies, dopant selection criteria and global thermodynamic stability. From these criteria, we discover over one hundred computationally stable multi-anionic compounds with indirect computed gaps EG > 1.5 eV (since PBE underestimates the gap) and average effective masses 0 < mh* < 1 by screening the Materials Project database. Several compounds studied previously as TCs emerge from our screening, including ZnS and sulvanites TaCu3X4 (X = S, Se, Te). We further pare down this list for synthesis by selecting only single anionic compounds, removing compounds with toxic and highly reactive elements, and estimating p-type dopability. A refined list of ten top experimentally-favorable candidates emerges and includes spinel ZnAl2S4, distorted rocksalt BaSnS2, and several other rocksalt structures. We will also present our initial attempts to combinatorially synthesize and characterize a few of the candidates, and lay out a roadmap for a future high-throughput screening, synthesis, characterization closed loop to enable new device paradigms using transparent conducting chalcogenides.