Abstract
In this work, we demonstrated a high-performance and long-lifetime inverted polymer solar cell employing PBD as electron transport layer. The active layer was a bulk heterojunction (BHJ) consisting of blending of poly(3-hexylthiophene)(P3HT) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) in 1, 2-Dichlorobenzene, with the inverted device structure：ITO / PBD / P3HT:PCBM / PEDOT / Ag. We discovered the performance of the device became better though continuous measuring the device. Eliminating reasons by many aftertreatments, the only method found to greatly enhance the performance is continued light soaking the device by using the solar simulator. After continuous light soaking two hours, this approach improves the short-circuit current from11.70mA/cm2 to 13.10mA/cm2, open-circuit voltage from 0.32V to 0.61V, fill factor from 0.29 to 0.60, and power conversion efficiency from 1.11% to 4.79%.(AM1.5G 100 mW/cm2) We also traced lifetime of the device, all devices were encapsulated and stored in an ambient atmosphere. The device using Cs2CO3 with deterioration more than 50% after 25 days, but the device using PBD increased slightly at first 16 days then decreased slowly. After 41 days the PCE maintained the same as fabricated. The lifetime of devices with PBD as ETL is much longer than those with Cs2CO3 as ETL.