Synthesis and Physical Properties of Solar MaterialCu$lt;inf$gt;1-x$lt;/inf$gt;Li$lt;inf$gt;x$lt;/inf$gt;InSe$lt;inf$gt;2$lt;/inf$gt;

Bulk materials of Li-doped Cu 1-x Li x InSe 2 (x = 0-0.4) were prepared by solid state reaction in evacuated and sealed quartz tubes at 873 K. To understand the physical properties of the materials, the structural, electrical and optical properties were systematically investigated. After doping with lithium, the samples crystallize in chalcopyrite structure with large grain sizes. Electrical resistivity and optical band gap of Li-doped Cu 1-x Li x InSe 2 are greatly enhanced to 2.7310 8 cm and 1.33 eV from original values of 1.9810 2 cm and 0.9 eV, respectively. The large band gap improves the open circuit voltage, indicating that the Li-doping CuInSe 2 could be a promising material to future photovoltaic applications.