Synthesis and Size-Dependent Optical Properties of Intermediate Band Gap Cu₃VS₄ Nanocrystals

Abstract

Intermediate band gap semiconductors are an underexplored class of materials with unique optical properties of interest for photovoltaic and optoelectronic applications. Herein, we synthesize highly crystalline cubic Cu3VS4 nanocrystals with tunable edge length of 9 nm, 12 nm and 18 nm. Since size-control is achieved for the first time for this semiconductor, particular emphasis is dedicated to the structural/compositional analysis, the formation mechanism and the size-dependent optical properties. The corresponding UV-Vis spectra reveal three absorption peaks in the visible range, resulting from the intermediate band gap electronic structure of Cu3VS4, which blue-shift with decreasing size. Density functional theory reveals these size-dependent optoelectronic properties to result mostly from weak quantum confinement. The reported results pave the way towards further fundamental investigations of the physicochemical properties of intermediate band gap semiconductors in the nanoscale regime for solar energy harvesting.

Synthesis and optoelectronic properties of Cu3VSe4 nanocrystals

“…It is worth noting that the XRD of V-NPs showed amorphous status. [10] Thus, we speculated that some amorphous V-NPs could be formed in the synthesized CVSe NCs. The fitted spectrum of Se 3d in Fig 3C presents a peak at 53.8 eV which can be attributed to the Se 3d 3/2 of Se 2-.…”

“…The report also demonstrated the presence of an intermediate bandgap (IB) in Cu 3 VS 4 through both theoretical calculations and experimental measurements. [10] Compared with photovoltaic devices with a single bandgap E g , semiconductors with an intermediate band can reduce the loss of incomplete absorption, since photons with energy below E g can also be absorbed through transitions from the valence band (VB) to IB or from IB to the conduction band (CB). [11] In addition, because of the multiple-band transitions of VB-IB and IB-CB, the intermediate band semiconductors were proposed to have the possibility to reduce the thermalization effect, compared with single-band semiconductors.…”

“…[12] Therefore, it is predicted that semiconductors with intermediate bands have the potential to increase the conversion efficiency of a solar cell as the consequent effect of highly exceeding the Schockley-Queisser limit up to 63.1%. [10,13] We anticipated that preparation of colloidal Cu 3 VSe 4 could be achieved via similar synthetic methodologies.…”

Shaping non-noble metal nanocrystals via colloidal chemistry

“…heterostructures, multimetallic alloys, multi-cation oxides and chalcogenides), including the same elements, which are becoming increasingly popular because of the additional property tunability offered by combining domains with a different chemical nature within the same nanodomain. [92][93][94][95][96][97][98][99][100][101]…”

“…The latter are then further reduced to metallic Cu aggregates which serve as seeds for the growth of the nanowires. The EDA acts as the surface passivating ligand inducing preferential growth along the [100] direction. Turning to the seeded-growth approach, penta-twinned Cu nanorods were obtained when using single-crystal Au and Pd twinned decahedra as seeds, with the latter leading to better size monodispersity.…”