Thin Film WSe2 for Use as a Photovoltaic Absorber Material
An excellent candidate for an earth abundant absorber material is WSe2 which can be directly grown as a p-type semiconductor with a band gap near 1.4 eV. In this work we present the structural, optical, and electrical properties of thin film WSe2 grown via the selenization of sputter deposited tungsten films. We will show that highly textured films with an optical band gap in range of 1.4 eV, and absorption coefficients greater than 105/cm across the visible spectrum can be easily achieved. In addition we will present Hall Effect and carrier density measurements as well, where will show densities in the 1017cm-3 range and p-type Hall mobilities greater than 10 cm2/V-s range can be obtained. We employ these results to numerically simulate solar cells based on this material, where we will show efficiencies greater than 20% are possible.