Spray deposition of poly(3-hexylthiophene) and [6, 6]-phenyl-C₆₁-butyric acid methyl ester blend under electric field for improved interface and organic solar cell characteristics

Spray process is used for the deposition of poly(3-hexylthiophene) (P3HT) and [6, 6]-phenyl-C₆₁-butyric acid methyl ester (PCBM) blend film under different voltages (0 V, 300 V, 500 V and 700 V) applied to the nozzle. The presence of the electric field during the spray process makes the P3HT:PCBM film smoother, uniform and more crystalline with well aligned domains. X-ray photoelectron spectroscopy study shows that PCBM rich surface is formed by application of the DC voltage (700 V) which improves the electron transport at the active layer and cathode interface. The application of electric field reduces the recombination at interfaces. The increased charge carrier separation between donor and acceptor at the interface and the crystallinity enhancement result in improved short circuit current density-voltage characteristics of Indium tin oxide/poly(3, 4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS)/P3HT:PCBM/Aluminum solar cell. The organic bulk-heterojunction solar cell using the electric field assisted spray deposited PEDOT:PSS and P3HT:PCBM layers exhibited 84% and 154% increment in the short circuit current density and power conversion efficiency, respectively in comparison to the solar cell having spray deposited PEDOT:PSS and P3HT:PCBM layers in the absence of the electric field.