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Solar Cells Dye Sensitized Devices Part 13

Tham khảo tài liệu 'solar cells dye sensitized devices part 13', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 352 Solar Cells - Dye-Sensitized Devices molecule stays longer at off time. The molecule in Fig.5 d should have relatively active electron transfer such that the fluorescence process is suppressed. Fig.5 d is used as an example. The fluorescence intensity trajectory is slotted within a 500-photon binned window to select one on intensity and the other off intensity Fig.6B a . Analyzing the fluorescence decay yields a result of 2.93 and 1.26 ns for the on 12.85 13.33 s slot and off 29.15 30.20 s slot lifetime respectively Fig.6B b . Given a threshold at 7 counts 20 ms the fluorescence intensity is divided to higher level and lower level. The lifetime analysis of these two levels yields the results similar to those obtained in the above time slots. The on state shows a twofold longer lifetime than the off state Fig.6B c . This fact indicates that the fluorescence intensity fluctuation is caused by both factors of reactivity i.e. the fraction of IFET occurrence frequency Wang et al. 2009 and rate of electron transfer. The fluorescence lifetimes analyzed within 0.5s-window fluctuate in a range from 0.6 to 4.8 ns which is more widely scattered than those acquired on the bare glass Fig.6B d . This phenomenon suggests existence of additional depopulation pathway which is ascribed to ET between oxazinel and TiC 2. However other contribution such as rotational and translational motion of the dye on the TiC 2 film can not be rule out without information of polarization dependence of the fluorescence. 3.3 Autocorrelation analysis An autocorrelation function based on the fluorescence intensity trajectory is further analyzed when the dye molecules are adsorbed on the TiC 2 NPs surface a four-level energy scheme is formed including singlet ground singlet excited and triplet states of the dye molecule as well as conduction band of TiC 2. Upon irradiation with a laser source the excited population may undergo various deactivation processes. Because the selected dye molecule has a .