Greatly Reduced Processing Temperature for a Solution-Processed NiO_x Buffer Layer in Polymer Solar Cells

摘要

By application of thermal annealing and UV ozone simultaneously, a solution-processed NiO_x film can achieve a work function of approximately -5.1 eV at a temperature below 150 ℃, which allows the processing of NiO_x that is compatible with fabrication of polymer solar cells (PSCs) on plastic substrates. The low processing temperature, which is greatly reduced from 250-400℃ to 150℃, is attributed to the high concentration of NiOOH species on the film surface. This concentration will result in a large surface dipole and lead to increased work function. The pretreated NiO_x is demonstrated to be an efficient buffer layer in PSCs based on polymers with different highest occupied molecular orbital energy levels. Compared with conventional poly(3,4-ethylenedioxy-thiophene):poly(styrenesulfonate)-buffered PSCs, the NiO_x-buffered PSCs achieve similar or improved device performance as well as enhanced device stability.