Performance improvement of TiO2∕P3HT solar cells using CuPc as a sensitizer

Abstract

In this work, a new type of TiO2/polymer solar cells was fabricated. The device structure was indium tin oxide titanium dioxide (TiO2)/ copper phthalocyanine (CuPc)/poly(3-hexylthiophene) (P3HT)/Au. In this architecture, TiO2 was designed to act as electron acceptor, and P3HT was electron donor. CuPc was used as a sensitizer to enhance photon absorption. The results show that by inserting CuPc between P3HT and TiO2 layers, the light absorption, excitons separation, and photocurrent under illumination are dramatically improved. The device has a short current density (JSC) of 1.15mA∕cm2 and power conversion efficiency (η) of 0.28% without CuPc layer. However, JSC and η turn to be 2.22mA∕cm2 and 0.66%, respectively, with a 20nm thickness CuPc layer under air mass 1.5 global (AM1.5G) illumination with the intensity of 100mW∕cm2. The performance improvement can be attributed to the higher carrier mobility and the stronger photon absorption using CuPc as a sensitizing layer.