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Role of Emissive and Non‐Emissive Complex Formations in Photoinduced Electron Transfer Reaction of CdTe Quantum Dots
摘要： Bimolecular photoinduced electron transfer (PET) from excited state CdTe quantum dot (QD*) to an electron deficient molecule 2,4-dinitrotoluene (DNT) is studied in toluene. We observed two types of QD-DNT complex formations; (i) non-emissive complex, in which DNT is embedded deep inside the surface polymer layer of QD and (ii) emissive complex, in which DNT molecules are attached to QDs but approach to the QD core is shielded by polymer layer. Because of its non-emissive nature, the lifetime of QD is not affected by dark complex formation, though the steady-state emission is greatly quenched. However, emissive complex formation causes both, lifetime and steady-state emission quenching. In our fitting model, consideration of Poisson distribution of the attached quencher (DNT) molecules at QD surface enables a comprehensive fitting to our time resolved data. QD-DNT complex formation was confirmed by an isothermal titration calorimetry (ITC) study. Fitting to the time resolved data using a stochastic kinetic model shows moderate increase (0.05 ns(cid:2)1 to 0.072 ns(cid:2)1) of intrinsic quenching rate with increasing the QD particle size (from (cid:3) 3.2 nm to (cid:3) 5.2 nm). Our fitting also reveals that the number of DNT molecules attached to a single QD increases from (cid:3) 0.1–0.2 to (cid:3) 1.2–1.7, as the DNT concentration is increased from (cid:3) 1 mm to 17.5 mm. Complex formation at higher quencher concentration assures that the observed PET kinetics is a thermodynamically controlled process where solvent diffusion has no role on it.
关键词： CdTe quantum dot,photo-induced electron transfer,donor-acceptor complex,time-resolved spectroscopy,fluorescence quenching
更新于2025-09-19 17:13:59
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Scattering property of aqueous solution of CdTe quantum dots with gold nanoparticles
摘要： We prepared the aqueous solution of CdTe quantum dots with gold nanoparticles by chemical crystal growth method. We simulated the scattering property of aqueous solution of CdTe quantum dots with gold nanoparticles using Finite Difference Time Domain(FDTD) method and verified by absorption spectrophotometer. Compared with aqueous solution of CdTe quantum dots, it has stronger absorption and emission spectrum. And its scattering intensity is enhanced about 1.5 times than CdTe quantum dots. The result can be used widely in the medicine field and optical field.
关键词： Scattering,Gold nanospheres,FDTD,CdTe quantum dot
更新于2025-09-16 10:30:52
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CdTe Sensitized Nano Porous Electrode for Photovoltaic Application
摘要： CdTe quantum dots were synthesized using water as a solvent medium. Synthesized quantum dots were used to integrate into TiO2 nano-porous electrode using a combination of linker assisted direct adsorption and chemical bath deposition process. Sensitized electrodes were characterized to understand their physical and optical properties for photovoltaic application.
关键词： nano porous electrode,CdTe quantum dot
更新于2025-09-12 10:27:22