Method of making photovoltaic devices with reduced conduction band offset between pnictide absorber films and emitter films

The principles of the present invention are used to reduce the conduction band offset between chalcogenide emitter and pnictide absorber films. Alternatively stated, the present invention provides strategies to more closely match the electron affinity characteristics between the absorber and emitter components. The resultant photovoltaic devices have the potential to have higher efficiency and higher open circuit voltage. The resistance of the resultant junctions would be lower with reduced current leakage. In illustrative modes of practice, the present invention incorporates one or more tuning agents into the emitter layer in order to adjust the electron affinity characteristics, thereby reducing the conduction band offset between the emitter and the absorber. In the case of an n-type emitter such as ZnS or a tertiary compound such as zinc sulfide selenide (optionally doped with Al) or the like, an exemplary tuning agent is Mg when the absorber is a p-type pnictide material such as zinc phosphide or an alloy of zinc phosphide incorporating at least one additional metal in addition to Zn and optionally at least one non-metal in addition to phosphorus. Consequently, photovolotaic devices incorporating such films would demonstrate improved electronic performance.