For the application of colloidal semiconductor quantum dots in optoelectronic devices, for example, solar cells and light-emitting diodes, it is crucial to understand and control their charge transport and recombination dynamics at high carrier densities. Both can be studied in ambipolar, light-emitting field-effect transistors (LEFETs). Here, we report the first quantum dot light-emitting tran...

Nonblinking excitonic emission from near-infrared and type-II nanocrystal quantum dots (NQDs) is reported for the first time. To realize this unusual degree of stability at the single-dot level, novel InP/CdS core/shell NQDs were synthesized for a range of shell thicknesses (~1-11 monolayers of CdS). Ensemble spectroscopy measurements (photoluminescence peak position and radiative lifetimes) an...

The radiative and nonradiative decay rates of lissamine dye molecules, chemically attached to differently sized gold nanoparticles, are investigated by means of time-resolved fluorescence experiments. A pronounced fluorescence quenching is observed already for the smallest nanoparticles of 1 nm radius. The quenching is caused not only by an increased nonradiative rate but, equally important, by...

In this study we introduce a new method for the one-pot synthesis of core/shell/shell alloyed Cd1-xZnxSe/ZnSe/ZnS QDs and examine the effect of the shell coating on the optical properties and exciton dynamics of the alloy core. The photoluminescence (PL) quantum yield is greatly enhanced after shell growth, from 9.6% to 63%. The exciton dynamics were studied by time correlated single photon cou...

While addition of electrolyte to sodium dodecyl sulfate suspensions of single-wall carbon nanotubes has been demonstrated to result in significant brightening of the nanotube photoluminescence (PL), the brightening mechanism has remained unresolved. Here, we probe this mechanism using time-resolved PL decay measurements. We find that PL decay times increase by a factor of 2 on addition of CsCl ...

We have investigated the effects of nonradiative recombination centers (NRCs) on the device performances of InGaN/GaN multi-quantum-well (MQW) light-emitting diodes (LEDs) incorporating low-temperature n-GaN (LT-GaN) underlying layers. Inserting an LT-GaN underlying layer prior to growing the MQWs is a successful means of separating the induced NRCs as a result of the presence of a growth inter...

We investigate the effect of free carrier dynamics on heat transport in bulk crystalline Silicon following femtosecond optical excitation varying fluences. By taking advantage dense 500 MHz standard fill pattern PLS-II storage ring, we perform high angular-resolution X-ray diffraction measurements nanosecond-to-microsecond time-scales with femtometer spatial sensitivity. find noticeably slowed ...

Slowing the degradation of perovskite-based solar cells (PSCs) is substantial interest. We engineered surface by introducing a hydrophobic overlayer on three-dimensional (3D) perovskite using fluorinated or nonfluorinated aryl ammonium cation spacers. The placement fluoroarene allows formation bilayer structure, that is, layered/3D perovskites. By doing so, character increases notably virtue pe...

A new analytical expression that directly relates the open-circuit voltage (Voc) in perovskite solar cells (PSCs) to quasi-Fermi level splitting (QFLS), interface energy offsets, and nonradiative recombination losses has been derived. It is found QFLS of active layer plays a dominant role enhancing Voc PSCs. The newly derived applied two PSCs with hole transport (HTL) poly[bis(4-phenyl)(2,4,6-t...

The temperature characteristics of bipolar cascade lasers operating up to 80 °C with room temperature, continuous-wave differential slope efficiencies of 93%, are reported. The continuous-wave characteristic lasing threshold temperature, T0 , of the device is found to be 103 K for heatsink temperatures below 40 °C, dropping to 56 K for heatsink temperatures in the range 50–80 °C. Two separate r...