Effect of Aging and PCBM Content on Bulk Heterojunction Organic Solar Cells Studied by Intensity Modulated Photocurrent Spectroscopyстатья
Статья опубликована в высокорейтинговом журнале
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Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 9 декабря 2016 г.
Аннотация:A series of encapsulated and non-encapsulated bulk heterojunction photovoltaic devices containing poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) with different P3HT:PCBM ratios were investigated using traditional steady state as well as non-steady state intensity modulated photocurrent spectroscopy (IMPS) techniques. The steady state J-V measurements showed that PCBM content did not have a significant effect on the efficiency for freshly prepared devices, whereas aged non-encapsulated devices exhibited a strong dependence on PCBM content. IMPS measurements showed a significant contribution of interfacial non-geminate recombination in non-encapsulated devices, which increased with decreasing PCBM content in the photoactive layer and cell aging. It was related to the formation of interfacial states at the P3HT/PCBM interface due to atmospheric contamination, which act as recombination centers. Device encapsulation was found to be effective in preventing the occurrence of interfacial recombination. Our results suggest that IMPS can be used as a diagnostic tool to predict the performance of bulk heterojunction organic solar cells. If a solar cell shows the presence of interfacial states as indicated by semicircle arcs in quadrant I of the IMPS complex plane plots, it is most likely that its performance will deteriorate with time due to enhanced interfacial recombination, even without further exposure to atmospheric contaminations. We conclude that interfacial non-geminate recombination is an important degradation mechanism in organic solar cells, especially in case of exposure to atmospheric contaminants.