Progress in a-SiOx:H Thin Film Solar Cells with Patterned MgF2 Dielectric for Top Cell of Multi-Junction System

Abstract

We successfully designed and experimentally demonstrated an application of patterned MgF2 dielectric material at rear Al-doped ZnO (AZO)/Ag interface in thin film amorphous silicon oxide (a-SiOx:H) solar cells. When it was realized in practical device process, MgF2 coverage with patterned morphology was employed to allow for current flow between the AZO and Ag against highly resistive MgF2 material. On the basis of the suggested structure, we found an improvement in quantum efficiency of the solar cells with the patterned MgF2. In addition, an enhancement of open circuit voltage (V-oc) and fill factor (FF) was observed. A remarkable increase in shunt resistance of the cells with the MgF2 would possibly indicate that the highly resistive MgF2 layer can partly suppress physical shunting across top and bottom electrodes caused by very thin absorber thickness of only 100 nm. The approach showed that our best-performing device revealed an essential improvement in conversion efficiency from 7.83 to 8.01% with achieving markedly high V-oc (1.013 V) and FF (0.729).