Improved Cathode Interface Contact in Poly(3-hexylthiophene) and 1-(3-Methoxycarbonyl)-propyl-1-phenyl-(6,6)C61 Based Organic Bulk Heterojunction Solar Cells by Introducing Compressive Stress

The authors investigate the effects of compressive stress on the performance of organic solar cells based on poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) blends. The short-circuit current density is improved, and a maximum 16% enhancement in power conversion efficiency is achieved by introducing suitable a stress into the device. The improved performance is attributed to the formation of a good contact between the Al cathode and the P3HT:PCBM blend owing to the introduction of a suitable compressive stress. Meanwhile, the barrier height at Al/blend is lowered from 0.34 to 0.23 eV by evaluating the temperature dependence of the current--voltage characteristics.