Influence of NiO anode buffer layer prepared by solution on performance of bulk-heterojunction solar cells

We investigate the properties of NiO thin films prepared by sol–gel solution and the photovoltaic performance of bulk-heterojunction (BHJ) solar cells based on NiO thin films as anode buffer layers with various film thickness and amorphous–crystalline phase. Optoelectronic properties and surface morphology of NiO films strongly depend on the thickness and phase of the NiO. The performance of solar cells based on nanocrystaline (nc-) NiO exhibits better photovoltaic characteristics in comparison to those employing an amorphous (a-) NiO. The obtained power conversion efficiency (PCE, η) of a solar cell with a 20-nm-thick nc-NiO is 2.24%, with a short-circuit density (JSC) of 7.77 mA/cm2, open-circuit voltage (VOC) of 0.57 V, and fill factor (FF) of 0.50.