Transparent flexible organic solar cells with 6.87% efficiency manufactured by an all-solution process.

We demonstrate that polyaniline (PANI) behaves as an anode buffer layer, which makes it an excellent hole transport layer. PANI was coated between the photoactive layer and the top anode in transparent flexible organic solar cells (OSCs). The performances of the devices with different PANI thicknesses were investigated. The results demonstrate that the power conversion efficiency (PCE) increased nearly four-fold with an 18 nm thick PANI layer compared to the reference cell without PANI. The optimum device performance with an 18 nm PANI layer exhibits a Jsc of 11.60 mA cm(-2), a V(oc) of 0.89 V, a FF of 66.87%, and thus a PCE of 6.87% under AM1.5G illumination of 100 mW cm(-2). The conversion efficiency of transparent flexible OSCs changes after 1500 bending cycles.