Low-temperature indium molybdenum oxide as a window layer in CIGS photovoltaic devices

High mobility transparent conductive oxides (HMTCO) have the distinguishing property of a higher near infrared (NIR) transmittance when compared with ordinary transparent conducting oxides (TCO). The use of HMTCO as a window layer in CIGS PV cells is expected to increase device efficiency by extending the spectral response and increasing photocurrent. In this work, low temperature sputter-deposited IMO (LTIMO) has been developed with resistivitiy of 10^-3 Ω-cm, and an average optical transmittance of nearly 80% over the visible range. An investigation into the use of this LTIMO as a window layer in CIGS solar cell applications is presented. Results from a comparative study of CIGS PV devices shows that incorporating indium-tin-oxide (ITO) versus LTIMO yields modest improvements in photovoltaic conversion efficiency attributable to the benefits of LTIMO. Follow-on investigations are currently underway to further optimize the LTIMO sputtering process for additional PV device improvements.