Metal salt modified PEDOT : PSS as anode buffer layer and its effect on power conversion efficiency of organic solar cells

The effects of metal chlorides such as LiCl, NaCl, CdCl2 and CuCl2 on optical transmittance, electrical conductivity as well as morphology of PEDOT:PSS films have been investigated. Transmittance spectra of spun PEDOT:PSS layers were improved by more than 6 to a maximum of 94 in LiCl doped PEDOT:PSS film. The surface of the PEDOT:PSS films has exhibited higher roughness associated with an increase in the electrical conductivity after doping with metal salts. The improvement in the physical properties of PEDOT:PSS as the hole transport layer proved to be key factors towards enhancing the P3HT:PCBM bulk heterojunction (BHJ) solar cells. These improvements include significantly improved power conversion efficiency with values as high as 6.82 associated with high fill factor (61) and larger short circuit current density (�18 mA cm-2). Keywords: Chlorine compounds; Conversion efficiency; Electric conductivity; Electrodes; Heterojunctions; Metals; Semiconductor doping; Solar cells, Electrode modification; Metal salt; Organic solar cell; P3HT:PCBM; PEDOT:PSS, Conducting polymers