Effect of Post-Annealing Treatment on the Contact Resistance of Small Molecule Solar Cells

Small molecule solar cells with structure of ITO/ZnPc/C60/LiF/Al were fabricated by vacuum evaporation method, and thermal annealing treatment was considered to be an effective and economized approach to further improve the power conversion efficiency and lifetime of devices. The optimal annealing process was 100°C, 20min in air ambient, and it respectively promoted the power conversion efficiency by 2.4 times and the stability of unencapsulated devices by 4.4 times As a conclusion, the main reason is attributed to the decrease of contact resistance. Moreover, the improvement of interfacial morphology at the ITO/ZnPc interface contributes the benefit.