title: Direct measurements of intersystem crossing rates and triplet decays of luminescent conjugated oligomers in solutions.
abstract: Photothermal calorimetry and fluorescence spectroscopy were used to determine the relaxations of the photoexcited singlet state of two PPV and polyfluorene oligomers, (E,E)-1,4-bis[(2-benzyloxy)styryl]benzene (PVDOP) and ter(9,9'-spirobifluorene) (TSBF). The decay rates of different S1 relaxation channels, which include intersystem crossing (ISC), radiative, and nonradiative decay can be determined by the combination of photoacoustic calorimetry (PAC) and the time-correlated single photon counting (TCSPC) technique. The triplet state energy level is determined by the phosphorescence (Ph) spectra recorded at 77 K. The ISC yields are approximately 3% and 6% for PVDOP and TSBF, respectively. The T1 to S0 transition decay rate is acquired by PAC and photothermal beam deflection (PBD) measurements. The triplet state decay rate is 17 and 21 ms(-1) at room temperature. The Ph intensity decay at 77 K shows that the triplet state lifetime increases by 4 orders of magnitude, as compared to room temperature.
authors: Department of Physics, National Taiwan University, Taipei 106, Taiwan.
authors: Hsin-Liang
authors: HL
authors: Chen
authors: Yi-Fang
authors: YF
authors: Huang
authors: Chao-Ping
authors: CP
authors: Hsu
authors: Tsong-Shin
authors: TS
authors: Lim
authors: Li-Chung
authors: LC
authors: Kuo
authors: Man-kit
authors: MK
authors: Leung
authors: Teng-Chih
authors: TC
authors: Chao
authors: Ken-Tsung
authors: KT
authors: Wong
authors: Show-An
authors: SA
authors: Chen
authors: Wunshain
authors: W
authors: Fann