Semiconductors group

Abstract:

The motivation for this research is that the emission spectra using directly pumped laser diodes have not yet been found. We want to explore the luminescence properties of a co-doped laser material utilizing a diode laser as an optical pump. The research method used standard melt-quench and was stimulated by a laser diode (808 and 980 nm). The double doped of Nd³⁺- Er³⁺/Nd³⁺-Pr³⁺ ions with glasses system of lithium-fluorophosphate (LFP) had a strong band emission at 1056 nm, which transitioned at ⁴F_3/2 → ⁴I_11/2 and showed a drop in intensity from co-doping with Er³⁺ and Pr³⁺ ions. The fluorescence width at half maximum (FWHM) of the glasses is calculated to identify whether the sample may be used as a laser application. The FWHM values are found to be 22-28 nm. Decay time values were shown to decrease with increasing concentrations of Er³⁺ and Pr³⁺ ions and were used for energy transfer calculations. The Quantum Yields (QYs), efficiency in the transfer of energy and the possibility transfer energy were measured and calculated that confirm the possibility of energy transfer from Nd³⁺ to Er³⁺ and Pr³⁺ ions. Since, the emission spectrum at 1535 nm was found, this is a good reason for it to be used as an optical device.

Abstract:

Efficient charge-carrier transport is critical to the success of emergent semiconductors in photovoltaic applications. So far, disorder has been considered detrimental for charge-carrier transport, lowering mobilities and causing fast recombination. This work demonstrates that, when properly engineered, cation disorder in a multinary chalcogenide semiconductor can considerably enhance the charge-carrier mobility and extend the charge-carrier lifetime. Here, the properties of AgBiS₂ nanocrystals (NCs) are explored where Ag and Bi cation-ordering can be modified via thermal-annealing. Local Ag-rich and Bi-rich domains formed during hot-injection synthesis are transformed to induce homogeneous disorder (random Ag-Bi distribution). Such cation engineering results in a six-fold increase in the charge-carrier mobility, reaching ∼2.7 cm²V⁻¹s⁻¹ in AgBiS₂ NC thin films. It is further demonstrated that homogeneous cation disorder reduces charge-carrier localisation, a hallmark of charge-carrier transport recently observed in silver-bismuth semiconductors. This work proposes that cation-disorder engineering flattens the disordered electronic landscape, removing tail states that would otherwise exacerbate Anderson localisation of small polaronic states. Together, these findings unravel how cation-disorder engineering in multinary semiconductors can enhance the efficiency of renewable energy applications.

Abstract:

Harnessing nonequilibrium hot carriers from plasmonic metal nanostructures constitutes a vibrant research field with the potential to control photochemical reactions, particularly for solar fuel generation. However, a comprehensive understanding of the interplay of plasmonic hot-carrier-driven processes in metal/semiconducting heterostructures has remained elusive. In this work, we reveal the complex interdependence among plasmon excitation, hot-carrier generation, transport, and interfacial collection in plasmonic photocatalytic devices, uniquely determining the charge injection efficiency at the solid/liquid interface. Measuring the internal quantum efficiency of ultrathin (14–33 nm) single-crystalline plasmonic gold (Au) nanoantenna arrays on titanium dioxide substrates, we find that the performance of the device is limited by hot hole collection at the metal/electrolyte interface. Our solid- and liquid-state experimental approach, combined with ab initio simulations, demonstrates more efficient collection of high-energy d-band holes traveling in the [111] orientation, enhancing oxidation reactions on {111} surfaces. These findings establish new guidelines for optimizing plasmonic photocatalytic systems and optoelectronic devices