2017 Volume 30 Issue 5 Pages 569-575
The degradation mechanism of pentacene/C60 heterojunction solar cells under light irradiation was investigated by evaluating the current density-voltage (J-V) and the incident photon to current conversion efficiency (IPCE) characteristics. The solar cells with a structure of indium tin oxide (ITO)/hole transport layer (HTL)/pentacene/C60/BCP/Al were fabricated using the HTL of poly(3,4-ethylenedioxythiophene):poly(4-styrene sulfonate) (PEDOT:PSS) or glycerol-added PEDOT:PSS (G-PEDOT:PSS). A p-type semiconductor pentacene, an n-type semiconductor C60, and an exciton blocking layer bathocuproine (BCP) were used for the fabrication. From the analysis of the IPCE characteristics for the cells without the HTLs, the device degradation is found to be caused by the absorption in pentacene at the wavelength range between ~320 and ~370 nm. Moreover, the insertion of the HTLs into the cells is found to be effective for preventing the performance degradation under light irradiation.