TY - JOUR
T1 - Influence of phase segregation on recombination dynamics in organic bulk-heterojunction solar cells
AU - Baumann, Andreas
AU - Savenije, Tom J.
AU - Murthy, Dharmapura Hanumantharaya K.
AU - Heeney, Martin
AU - Dyakonov, Vladimir
AU - Deibel, Carsten
N1 - Generated from Scopus record by KAUST IRTS on 2023-02-14
PY - 2011/5/10
Y1 - 2011/5/10
N2 - The recombination dynamics of charge carriers in organic bulk-heterojunction (BHJ) solar cells made of the blend system poly(2,5-bis(3-dodecylthiophen-2-yl) thieno[2,3-b]thiophene) (pBTCT-C 12 ):[6,6]-phenyl-C 61 -butyric acid methyl ester (PC 61 BM) with a donor-acceptor ratio of 1:1 and 1:4 are studied here. The techniques of charge-carrier extraction by linearly increasing voltage (photo-CELIV) and, as local probe, time-resolved microwave conductivity are used. A difference of one order of magnitude is observed between the two blends in the initially extracted charge-carrier concentration in the photo-CELIV experiment, which can be assigned to an enhanced geminate recombination that arises through a fine interpenetrating network with isolated phase regions in the 1:1 pBTCTC 12 :PC 61 BM BHJ solar cells. In contrast, extensive phase segregation in 1:4 blend devices leads to an efficient polaron generation that results in an increased shortcircuit current density of the solar cells. For both studied ratios a bimolecular recombination of polarons is found using the complementary experiments. The charge-carrier decay order of above two for temperatures below 300 K can be explained on the basis of a release of trapped charges. This mechanism leads to delayed bimolecular recombination processes. The experimental findings can be generalized to all polymer:fullerene blend systems allowing for phase segregation. © 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
AB - The recombination dynamics of charge carriers in organic bulk-heterojunction (BHJ) solar cells made of the blend system poly(2,5-bis(3-dodecylthiophen-2-yl) thieno[2,3-b]thiophene) (pBTCT-C 12 ):[6,6]-phenyl-C 61 -butyric acid methyl ester (PC 61 BM) with a donor-acceptor ratio of 1:1 and 1:4 are studied here. The techniques of charge-carrier extraction by linearly increasing voltage (photo-CELIV) and, as local probe, time-resolved microwave conductivity are used. A difference of one order of magnitude is observed between the two blends in the initially extracted charge-carrier concentration in the photo-CELIV experiment, which can be assigned to an enhanced geminate recombination that arises through a fine interpenetrating network with isolated phase regions in the 1:1 pBTCTC 12 :PC 61 BM BHJ solar cells. In contrast, extensive phase segregation in 1:4 blend devices leads to an efficient polaron generation that results in an increased shortcircuit current density of the solar cells. For both studied ratios a bimolecular recombination of polarons is found using the complementary experiments. The charge-carrier decay order of above two for temperatures below 300 K can be explained on the basis of a release of trapped charges. This mechanism leads to delayed bimolecular recombination processes. The experimental findings can be generalized to all polymer:fullerene blend systems allowing for phase segregation. © 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
UR - https://onlinelibrary.wiley.com/doi/10.1002/adfm.201002358
UR - http://www.scopus.com/inward/record.url?scp=79957625405&partnerID=8YFLogxK
U2 - 10.1002/adfm.201002358
DO - 10.1002/adfm.201002358
M3 - Article
SN - 1616-301X
VL - 21
SP - 1687
EP - 1692
JO - Advanced Functional Materials
JF - Advanced Functional Materials
IS - 9
ER -