TY - JOUR
T1 - 2,5-di(thiophen-2-yl)thiazolo[5,4-d]thiazole-based donor-acceptor type copolymers for photovoltaic cells
AU - Jeong, Eunjae
AU - Kim, Gi Hwan
AU - Jung, In Hwan
AU - Jeong, Pyeongsu
AU - Kim, Jin Young
AU - Woo, Han Young
N1 - Funding Information:
This work was supported by Basic Science Research Program through the NRF funded by the Ministry of Education, Science and Technology ( 2009-00605, 2010-0007431, R31-2008-000-20012-0 ) and New & Renewable Energy R&D program (2008-N-PV08-P-01) under the Korea Ministry of Knowledge Economy (MKE).
PY - 2012/1
Y1 - 2012/1
N2 - Alternating donor-acceptor type copolymers, poly[{5,11-di(9′- heptadecanyl)indolo[3,2-b]carbazole}-alt-{2,5-di(thiophen-2-yl)thiazolo[5,4-d] thiazole-5,5′-diyl}] (PIC-TZ) and poly[{6,6′,12,12′- tetraoctylindeno[1,2-b]fluorene}-alt-{2,5-di(thiophen-2-yl)thiazolo[5,4-d] thiazole-5,5′-diyl}] (PIF-TZ), were synthesized and examined for applications in polymeric photovoltaic cells. The polymers have a fused coplanar main backbone with good planarity for intermolecular packing and high charge mobility. The indolocarbazole and indenofluorene units contain two or four binding sites for alkyl substituents that have pronounced solution processiblity compared to the carbazole and fluorene moieties. The number-average molecular weights (Mn) of the synthesized polymers were determined to be 11,000 g/mol (PDI = 2.27) for PIC-TZ, and 17,000 g/mol (PDI = 1.77) for PIF-TZ. The optical band gap of PIC-TZ and PIF-TZ in film was determined to be 2.14 eV and 2.21 eV, respectively, and an electrochemical study confirmed the desirable HOMO/LUMO levels of the copolymers, which enabled efficient electron transfer and a high open circuit voltage (VOC) when blending them with fullerene derivatives. The space charge limited current mobility measurements showed a hole mobility of 10-3 cm2 V-1 s -1 for the copolymers. When the polymers were blended with [6,6]phenyl-C61-butyric acid methyl ester (PCBM), PIC-TZ showed the best performance with VOC, short-circuit current and power conversion efficiency of 0.86 V, 4.16 mA/cm2 and 1.64%, respectively, under AM 1.5G illumination conditions (100 mW cm-2).
AB - Alternating donor-acceptor type copolymers, poly[{5,11-di(9′- heptadecanyl)indolo[3,2-b]carbazole}-alt-{2,5-di(thiophen-2-yl)thiazolo[5,4-d] thiazole-5,5′-diyl}] (PIC-TZ) and poly[{6,6′,12,12′- tetraoctylindeno[1,2-b]fluorene}-alt-{2,5-di(thiophen-2-yl)thiazolo[5,4-d] thiazole-5,5′-diyl}] (PIF-TZ), were synthesized and examined for applications in polymeric photovoltaic cells. The polymers have a fused coplanar main backbone with good planarity for intermolecular packing and high charge mobility. The indolocarbazole and indenofluorene units contain two or four binding sites for alkyl substituents that have pronounced solution processiblity compared to the carbazole and fluorene moieties. The number-average molecular weights (Mn) of the synthesized polymers were determined to be 11,000 g/mol (PDI = 2.27) for PIC-TZ, and 17,000 g/mol (PDI = 1.77) for PIF-TZ. The optical band gap of PIC-TZ and PIF-TZ in film was determined to be 2.14 eV and 2.21 eV, respectively, and an electrochemical study confirmed the desirable HOMO/LUMO levels of the copolymers, which enabled efficient electron transfer and a high open circuit voltage (VOC) when blending them with fullerene derivatives. The space charge limited current mobility measurements showed a hole mobility of 10-3 cm2 V-1 s -1 for the copolymers. When the polymers were blended with [6,6]phenyl-C61-butyric acid methyl ester (PCBM), PIC-TZ showed the best performance with VOC, short-circuit current and power conversion efficiency of 0.86 V, 4.16 mA/cm2 and 1.64%, respectively, under AM 1.5G illumination conditions (100 mW cm-2).
KW - Low band gap polymers
KW - Photovoltaic cells
KW - Polymer solar cells
UR - http://www.scopus.com/inward/record.url?scp=80054802457&partnerID=8YFLogxK
U2 - 10.1016/j.cap.2011.04.019
DO - 10.1016/j.cap.2011.04.019
M3 - Article
AN - SCOPUS:80054802457
VL - 12
SP - 11
EP - 16
JO - Current Applied Physics
JF - Current Applied Physics
SN - 1567-1739
IS - 1
ER -