Exploring Cu-Doping for Performance Improvement in Sb 2 Se 3 Photovoltaic Solar Cells.

Copper-doped antimony selenide (Cu-doped Sb 2 Se 3 ) thin films were deposited as absorber layers in photovoltaic solar cells using the low-temperature pulsed electron deposition (LT-PED) technique, starting from Sb 2 Se 3 targets where part of the Sb was replaced with Cu. From a crystalline point of view, the best results were achieved for thin films with about Sb 1.75 Cu 0.25 Se 3 composition. In order to compare the results with those previously obtained on undoped thin films, Cu-doped Sb 2 Se 3 films were deposited both on Mo- and Fluorine-doped Tin Oxide (FTO) substrates, which have different influences on the film crystallization and grain orientation. From the current-voltage analysis it was determined that the introduction of Cu in the Sb 2 Se 3 absorber enhanced the open circuit voltage (V OC ) up to remarkable values higher than 500 mV, while the free carrier density became two orders of magnitude higher than in pure Sb 2 Se 3 -based solar cells.