Effect of Annealing on Performance of Solar Cells with New Oxide Absorber Mn2V2O7

All-oxide solar cells are attractive due to their stability, low cost and ease of fabrication. Very few oxide-absorbers are known and the efficiencies are limited by low mobility and lifetimes. In this work, for the first time, photovoltaic properties of a new oxide semiconductor, Mn2V207 (MVO) are described. Optical measurements show that MVO has an indirect bandgap of 1.6 eV and a direct bandgap of 1.75 eV, which suggests that it absorbs efficiently in the visible region of the solar spectrum. The valence and conduction band positions of the intrinsically n-doped MVO film are determined to be at 5.5 eV and 3.9 eV. Schottky solar cells fabricated using Pt/MVO heterojunction show low short circuit current (Jsc) and open circuit voltage (Voc). Annealing in nitrogen ambience results in a Jsc of 0.46 mA/cm2 a 50x increase and of Voc 0.21 V, almost 10x increase compared to un-annealed device. A maximum power of 24.1 μcm2is obtained, which is two orders of magnitude higher than un-annealed devices.