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Effect of Polymer Crystallinity in P3HT:PCBM Solar Cells on Band Gap Trap States and Apparent Recombination Order
Author(s) -
Spoltore Donato,
Oosterbaan Wibren D.,
Khelifi Samira,
Clifford John N.,
Viterisi Aurelien,
Palomares Emilio,
Burgelman Marc,
Lutsen Laurence,
Vanderzande Dirk,
Manca Jean
Publication year - 2013
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201200674
Subject(s) - materials science , recombination , crystallinity , band gap , charge carrier , chemical physics , polymer , polymer solar cell , solar cell , optoelectronics , chemistry , biochemistry , composite material , gene
The non‐geminate recombination of charge carriers in polymer‐fullerene solar cells has been modeled in the last few years with a trap‐assisted recombination model, which states that the apparent recombination order depends on the concentration of trapped charges tailing into the band gap. Higher concentrations of trapped charges lead to higher apparent recombination orders. In this work, the mass fraction f of highly crystalline nanofibrillar P3HT to the total P3HT content in P3HT:PCBM solar cells is consistently varied, controlling the temperature of a nanofibers‐P3HT casting dispersion. A systematic study of the apparent recombination order, measured with a transient photovoltage technique, as a function of f is presented. A correlation is shown between the apparent recombination order, the P3HT crystallinity, and the trap concentration in the band gap measured with an admittance spectroscopy technique.