C. A. J. Lin

Recombination dynamics of photoluminescence in thiol-protected gold nanoclusters

Recombination dynamics of photoluminescence (PL) in Au nanoclusters (NCs) with different capping molecules were studied with time-resolved PL. Based on the emission-energy of carrier lifetimes; we suggest that the fast and slow PL decay of Au NCs originates from recombination of the linear Au–S bond and the staple motif, respectively. The effect of carrier localization in Au NCs was found to depend on the capping molecules. The zero-dimensionality of carriers in Au NCs was demonstrated by the temperature dependence of the time-resolved PL.

Efficient energy transfer from InGaN quantum wells to Ag nanoparticles

Nonradiative energy transfer from an InGaN quantum well to Ag nanoparticles is unambiguously demonstrated by the time-resolved photoluminescence. The distance dependence of the energy transfer rate is found to be proportional to 1/d(3), in good agreement with the prediction of the dipole interaction calculated from the Joule losses in acceptors. The maximum energy-transfer efficiency of this energy transfer system can be as high as 83%.

Interrelation of transport and optical properties in gold nanoclusters

Temperature dependence of the electrical conductivity and photoluminescence (PL) in Au nanoclusters (NCs) is investigated. The correlation of the conductivity and PL in Au NCs at different temperatures is evident: (i) for T<50 K, both the conductivity and PL intensity decrease with temperature, which suggests thermal structural fluctuations; (ii) for 50 K<T<90 K, conductivity and PL are explained by variable range hopping; (iii) for 90 K<T<170 K, simple thermal activated hopping dominates in conductivity, with a rate-equation model proposed to analyze the carrier transfer in PL.Temperature dependence of the electrical conductivity and photoluminescence (PL) in Au nanoclusters (NCs) is investigated. The correlation of the conductivity and PL in Au NCs at different temperatures is evident: (i) for T<50 K, both the conductivity and PL intensity decrease with temperature, which suggests thermal structural fluctuations; (ii) for 50 K<T<90 K, conductivity and PL are explained by variable range hopping; (iii) for 90 K<T<170 K, simple thermal activated hopping dominates in conductivity, with a rate-equation model proposed to analyze the carrier transfer in PL.

Improved light trapping in polymer solar cells by light diffusion ink

Light trapping is an important issue for solar cells to increase optical path length and optical absorption. In this work, a light trapping structure was realized for polymer solar cells by utilizing light diffusion ink which is conventionally used in display backlighting. The light scattering particles in the ink cause the deflection of light, and the number of these particles coated on a glass substrate determines the light transmission and scattering characteristics. It was observed that the short-circuit current density did not decrease with decreasing transmittance, but it increased to a highest value at an optimized transmittance. This behaviour is attributed to the trapping of scattered light in the photoactive layer.

Site-selective photoluminescence in thiol-capped gold nanoclusters

Photoluminescence (PL) from the thiol-capped Au nonoclusters (NCs) has been investigated under site-selective excitation. Upon scanning the excitation light with energy below 2.1 eV down to 1.6 eV, the PL narrows and begins shifting linearly with excitation energy. The time-resolved PL was studied and the PL decay traces of Au NCs were found to depend on the excitation and emission energies. The slow carrier relaxation in the localized states is suggested to be responsible for the line narrowing and peak-shift in the site-selective PL.

Waveguide based energy transfer with gold nanoclusters for detection of hydrogen peroxide

H2O2 detection that uses fluorescence resonance energy transfer from InGaN quantum wells to Au nanoclusters via optical waveguiding has been developed. Steady and time-resolved photoluminescence studies have been used to demonstrate the waveguide-based energy transfer. H2O2 detection is achieved by the quenching of the red emission from Au nanoclusters. Advantages of the sensing technique include the capability of visual detection and large area analysis.