Defect Engineering of Cuprous Oxide Thin-films for Photovoltaic Applications

Download or read book Defect Engineering of Cuprous Oxide Thin-films for Photovoltaic Applications written by Yun Seog Lee and published by . This book was released on 2013 with total page 119 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thin-film solar cells are promising for renewable-energy applications due to their low material usage and inexpensive manufacturing potential, making them compatible with terawatts-level deployment. Cuprous oxide (Cu2O) is an earthabundant semiconductor with desirable properties for light-absorbing layers. However, power conversion efficiencies of solar cells comprising this absorber material remain significantly below the theoretical limit. In this thesis, I utilize novel materials and device geometries to engineer defects in Cu2O thin-films and overcome the low power-conversion-efficiency of Cu 20-based solar cells. First, nitrogen doping is proposed as an effective p-type doping method to control optical and electrical properties of Cu2O thin-films. The film's p-type conductivity is elucidated by temperature-dependent Hall effect measurements and a compensated semiconductor model. Secondly, an atomic-layer-deposited amorphous zinc-tin-oxide buffer layer is developed to mitigate non-ideal band alignment and interfacial defect-assisted recombination in Cu2O - zinc oxide (ZnO) heterojunction devices. Reduced interfacial recombination is demonstrated by incorporating a 5-nm-thick buffer layer in the device. Finally, I propose a spatially controlled vertical ZnO nanowire array to overcome the short minority carrier diffusion length in Cu2O. A scalable fabrication process is developed using colloidal lithography and hydrothermal growth of ZnO nanowires. Optical simulations are also conducted to investigate the effect of nanostructured device geometry on light-absorption properties.