Efficiency improvement of electrospun TiO/sub 2/ nanofibers based double heterojunction organic photovoltaic devices by zno cathode buffer layer

Polymer/fullerene solar cells with cathode buffer layer and double heterojunction electrospun metal oxide nanofibers are presented in this study. Electrospun TiO/sub 2/ nanofibers on solution processed ZnO cathode buffer layer (CBL) are synthesized and introduced to inverted organic photovoltaic devices for improving their power conversion efficiency. It is found that a combination of ZnO (CBL) with electrospun TiO/sub 2/ nanofibers covers a large wavelength range for light absorption and reduced device series resistance, which improved current density and fill factor of the devices. The structural and optical properties of the various structure/ layers are investigated by FESEM and UV-Vis spectrophotometer, while the devices were characterized under 1.5G illuminations by solar simulator. The resultant efficient inverted solar cells exhibit an open circuit voltage of 0.62V, short circuit current density of 12.98mA/cm2, fill factor of 0.53 and power conversion efficiency of 4.27+-0.01%. (author)