Unified Study of Recombination in Polymer:Fullerene Solar Cells Using Transient Absorption and Charge-Extraction Measurements.
Recombination in the well-performing bulk heterojunction solar cell blend between the conjugated polymer TQ-1 and the substituted fullerene PCBM has been investigated with pump-probe transient absorption and charge extraction of photogenerated carriers (photo-CELIV). Both methods are shown to generate identical and overlapping data under appropriate experimental conditions. The dominant type of recombination is bimolecular with a rate constant of 7 × 10(-12) cm(-3) s(-1). This recombination rate is shown to be fully consistent with solar cell performance. Deviations from an ideal bimolecular recombination process, in this material system only observable at high pump fluences, are explained with a time-dependent charge-carrier mobility, and the implications of such a behavior for device development are discussed.
†Chemical Physics, Lund University, P.O. Box 124, SE-22100 Lund, Sweden.|‡Biomolecular and Organic Electronics, Department of Physics Chemistry and Biology (IFM), Linköping University, SE-58183 Linköping, Sweden.
L Mattias
LM
Andersson
‡Biomolecular and Organic Electronics, Department of Physics Chemistry and Biology (IFM), Linköping University, SE-58183 Linköping, Sweden.
Armantas
A
Melianas
†Chemical Physics, Lund University, P.O. Box 124, SE-22100 Lund, Sweden.
Yingyot
Y
Infahasaeng
‡Biomolecular and Organic Electronics, Department of Physics Chemistry and Biology (IFM), Linköping University, SE-58183 Linköping, Sweden.
Zheng
Z
Tang
†Chemical Physics, Lund University, P.O. Box 124, SE-22100 Lund, Sweden.
Arkady
A
Yartsev
‡Biomolecular and Organic Electronics, Department of Physics Chemistry and Biology (IFM), Linköping University, SE-58183 Linköping, Sweden.
Olle
O
Inganäs
†Chemical Physics, Lund University, P.O. Box 124, SE-22100 Lund, Sweden.
Villy
V
Sundström
bulk heterojunction solar cell; conjugated polymer; fullerene; recombination