Overcoming consistency constrains of ITO/ZnO/P3HT:PCBM/Ag solar cell by open air annealing and its systematic stability study under inborn conditions

Focusing on simplicity and industrial viability, polymer solar cells with configuration indium tin oxide (ITO)/ZnO/P3HT:PCBM/Ag were fabricated and characterized. Differing from the usual trend of using glove box for polymer device fabrication, here electron transport and active layer of the devices were deposited and stored in open air atmosphere without any encapsulation. Effect of active layer thickness on device performance was analyzed. Choosing the optimum thickness of 220 ± 20 nm, a number of devices were fabricated with same configuration and the effect of annealing on the photovoltaic parameters was investigated. Unlike annealing studies reported in literature, particular emphasis was given here to study the influence of annealing in ambient atmosphere, at temperature of 50 °C, for 30 s. This short period, low temperature annealing enhanced the device parameters mainly short circuit current density and hence efficiency. Lifetime measurements were done by monitoring the device and measuring its J–V parameters periodically for 1 year. X-ray photoelectron spectroscopy depth profile analysis was employed to demonstrate that surface modified ZnO effectively hinders the diffusion of indium from ITO to active layer.