TY - JOUR
T1 - Spectroscopic study of spin-dependent exciton formation rates in π-conjugated semiconductors
T2 - Comparison with electroluminescence techniques
AU - Yang, C.
AU - Vardeny, Z. V.
AU - Köhler, A.
AU - Wohlgenannt, M.
AU - Al-Suti, M. K.
AU - Khan, M. S.
N1 - Funding Information:
Funding is acknowledged from the Royal Society, UK (A.K.) and Sultan Qaboos University, Oman (M.S.K.). At the University of Utah this work was partially supported by the DOE, under Grant No. FG-02-04 ER 46109. At the University of Iowa, this work was supported by the Carver Foundation and NSF Grant No. ECS 04–23911.
PY - 2004/12
Y1 - 2004/12
N2 - It has been found in recent measurements that the singlet-to-triplet exciton ratio in organic light-emitting diodes (OLEDs) is larger than expected from spin degeneracy, and that singlet excitons form at a larger rate than triplets. We employed the technique of optically detected magnetic resonance to measure the spin-dependent exciton formation rates in films of a polymer and corresponding monomer, and explore the relation between the formation rates and the actual singlet-to-triplet ratio measured previously in OLEDs. We found that the spin-dependent exciton formation rates can indeed quantitatively explain the observed exciton yields, and that singlet formation rates and yields are significantly enhanced only in polymer OLEDs, but not in OLEDs made from the corresponding monomer.
AB - It has been found in recent measurements that the singlet-to-triplet exciton ratio in organic light-emitting diodes (OLEDs) is larger than expected from spin degeneracy, and that singlet excitons form at a larger rate than triplets. We employed the technique of optically detected magnetic resonance to measure the spin-dependent exciton formation rates in films of a polymer and corresponding monomer, and explore the relation between the formation rates and the actual singlet-to-triplet ratio measured previously in OLEDs. We found that the spin-dependent exciton formation rates can indeed quantitatively explain the observed exciton yields, and that singlet formation rates and yields are significantly enhanced only in polymer OLEDs, but not in OLEDs made from the corresponding monomer.
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U2 - 10.1103/PhysRevB.70.241202
DO - 10.1103/PhysRevB.70.241202
M3 - Article
AN - SCOPUS:14944356252
VL - 70
SP - 1
EP - 4
JO - Physical Review B - Condensed Matter and Materials Physics
JF - Physical Review B - Condensed Matter and Materials Physics
SN - 1098-0121
IS - 24
M1 - 241202
ER -