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Evaluating Carrier Accumulation in Degraded Bulk Heterojunction Organic Solar Cells by a Thermally Stimulated Current Technique
Author(s) -
Kawano Kenji,
Adachi Chihaya
Publication year - 2009
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.200901573
Subject(s) - materials science , degradation (telecommunications) , heterojunction , organic solar cell , charge carrier , annealing (glass) , photoactive layer , optoelectronics , polymer solar cell , solar cell , carrier lifetime , thermal , cathode , silicon , polymer , composite material , chemistry , telecommunications , physics , computer science , meteorology
Here, the initial photo‐degradation of encapsulated P3HT:PCBM bulk heterojunction organic solar cells is investigated. The degraded device is recovered by thermal annealing treatment. Thermally stimulated current measurements reveal that the cause of photo‐degradation is carrier accumulation and that the degraded organic solar cell has two broad trap levels, of 0.71 and 0.81 eV. These traps are independent of the thickness of the photoactive layers, the mixing ratio of the photoactive materials and the cathode materials. In addition, it is confirmed that there is a close relationship between the degree of degradation and the amount of accumulated charge carriers.