Abstract
Recently, inverted organic solar cells have been widely investigated since their life time is much longer than those of conventional ones. In this research, we prepared two different materials as electron transport layer and employed different fabrication methods to manufacture the inverted organic solar cell on flexible substrate. In this work, an inverted organic solar cell based on P3HT:PCBM were spin-coated on two different electron transport layers which are cesium carbonate (Cs2CO3) and zinc oxide (ZnO) thin films. With these oxides, they changed the work function of ITO and metal electrode by forming a thin dipole layer. In Cs2CO3 experiment series, we promoted the device performance and stability by reducing the annealing temperature and the spin rate of the Cs2CO3 layers. As a result, the power conversion efficiency (PCE) of the devices improved to 2.2%. In our main study, we changed the film thickness of ZnO. The devices exhibit a PCE of 3.78% with optimum film thickness. As deposition temperature of ZnO thin film increases from room temperature to 80oC, the PCE increases from 3.78% to 4.18%, which is the highest performance for polymer solar cell on flexible substrates.