Comparative Aging Study of Organic Solar Cells Utilizing Polyaniline and PEDOT:PSS as Hole Transport Layers

The aging effect on P3HT:PCBM organic solar cells was investigated with camphorsulfonic doped polyaniline (PANI:CSA) or poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) used as the hole transport layer (HTL). The cells were encapsulated and exposed to a continuous normal atmosphere on a dark shelf and then characterized intermittently for more than two years. The photovoltaic results revealed that the cells with PEDOT:PSS HTL showed better initial results than the cells with PANI:CSA HTL. Over time, PEDOT:PSS-based cells exhibited faster degradation than PANI:CSA-based cells, where the average efficiency of six cells dropped to zero in less than one and a half years. On the other hand, PANI:CSA-based cells exhibited a much more stable performance with an average efficiency drop of only 15% of their initial values after one and a half years and 63% after two years. A single-diode model was utilized to fit the experimental data with the theoretical curve to extract the diode parameters, such as the ideality factor, to explain the effect of aging on the diode's performance.