Browsing by Author "Wu, Chi-Hui"

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Enhanced photovoltaic response of organic solar cell by singlet-to-triplet exciton conversion
(2007-03-26)
Yang, Chia-Ming
;
Wu, Chi-Hui
;
Liao, Hua-Hsin
;
Lai, Kuei-Yuan
;
Cheng, Hong-Ping
Ir complex was doped to conjugated polymers, and the photoinduced absorption of triplet excitons in host materials was examined. A greatly enhanced intersystem crossing rate was observed, despite the decrease in triplet exciton lifetime. The authors find that the steady-state triplet exciton population in host polymer would increase by an order of magnitude. Conjugated polymer/colloidal CdSe nanocrystal hybrid solar cells were fabricated and the effect of Ir-complex doping on photovoltaic response was studied. It was found that due to the enhanced singlet-to-triplet conversion, greatly enhanced photovoltaic response of these hybrid organic solar cells was observed. The results suggest that triplet solar cells may be achieved by doping conventional photovoltaic materials with transition-metal complexes. (c) 2007 American Institute of Physics.
Large enhancement of intersystem crossing in polyfluorenes by iridium-complex doping
(2007-01-01)
Liao, Hua-Hsien
;
Yang, Chia-Ming
;
Wu, Chi-Hui
;
Horng, Sheng-Fu
;
Lee, Wei-Shan
Photoinduced absorption is used to study the intersystem crossing (ISC) rate of two polyfluorenes doped with iridium (III) tris[2-(4-totyl)pyridinato-N,C2]. It is found that the triplet exciton lifetime of polyfluorene is reduced by the dopants. But instead of decreasing, the population density of polyfluorene triplet exciton increases by almost one order of magnitude. The finding shows that the ISC rate can increase over 100 times due to the spin-orbital interaction with the Ir ion even though it is covered by the ligands. Specifically, the ISC lifetime changes from the intrinsic value of 62 ns to as short as 0.28 ns upon 10% doping.