Nonlinear Density Dependence of Singlet Fission Rate in Tetracene Films.
Singlet fission holds the potential to dramatically improve the efficiency of solar energy conversion by creating two triplet excitons from one photoexcited singlet exciton in organic semiconductors. It is generally assumed that the singlet-fission rate is linearly dependent on the exciton density. Here we experimentally show that the rate of singlet fission has a nonlinear dependence on the density of photoexcited singlet excitons in tetracene films with small crystalline grains. We disentangle the spectrotemporal features of singlet and triplet dynamics from ultrafast spectroscopic data with the algorithm of singular value decomposition. The correlation between their temporal dynamics indicates a superlinear dependence of fission rate on the density of singlet excitons, which may arise from excitonic interactions.
Bo
B
Zhang
Chunfeng
C
Zhang
Rui
R
Wang
‡New and Renewable Energy of Beijing Key Laboratory, School of Renewable Energy, North China Electric Power University, Beijing 102206, China.
Zhanao
Z
Tan
Yunlong
Y
Liu
Wei
W
Guo
Xiaoling
X
Zhai
Yi
Y
Cao
Xiaoyong
X
Wang
§Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, United States.
Min
M
Xiao
excitonic interaction; quantum beats; singular value decomposition; transient absorption