PEDOT:PSS-free organic solar cells using tetrasulfonic copper phthalocyanine as buffer layer

This work aims at designing a new poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)-free multilayered system for bulk heterojunction organic solar cells. We propose a multilayer structure of glass/indium tin oxide/tetrasulfonated copper phthalocyanine/poly(3-hexylthiophene):[6,6]-C61-butyric acid methyl ester/aluminum (ITO/TS-CuPc/P3HT:[60]PCBM/Al). In this architecture, the TS-CuPc is mainly used as a buffer layer instead of PEDOT:PSS and can also act as an electron-donor material and a hole-extraction layer. Photovoltaic devices with a short-circuit current density of 9.7 mA/cm2, a open-circuit voltage of 0.51 V, and a power conversion efficiency of 1.76% were achieved, without post deposition thermal treatment of the P3HT:[60]PCBM blend layer.