V-substituted In₂S₃: an intermediate band material with photocatalytic activity in the whole visible light range

Abstract

We proposed in our previous work V-substituted ln2S3asan intermediate band (IB) material able to enhance the efficiency of photovoltaic cells by combining two photons to achieve a higher energy electron excitation, much like natural photosynthesis. Here this hyper-doped material is tested in a photocatalytic reaction using wavelength-controlled light. The results evidence its ability to use photons with wavelengths of up to 750 nm, i.e. with energy significantly lower than the bandgap (=2.0 eV) of nonsubstituted ln2S3, driving with them the photocatalytic reaction at rates comparable to those of nonsubstituted ln2S3 in its photoactivity range (A < 650 nm). Photoluminescence spectra evidence that the same bandgap excitation as in V-free ln2S3 occurs in V-substituted ln2S3 upon illumination with photons in the same sub-bandgap energy range which is effective in photocatalysis, and its linear dependence on light intensity proves that this is not due to a nonlinear optical property. This evidences for the first time that a two-photon process can be active in photocatalysis in a single-phase material. Quantum calculations using GW-type many-body perturbation theory suggest that the new band introduced in the ln2S3 gap by V insertion is located closer to the conduction band than to the valence band, so that hot carriers produced by the two-photon process would be of electron type; they also show that the absorption coefficients of both transitions involving the IB are of significant and similar magnitude. The results imply that V-substituted ln2S3, besides being photocatalytically active in the whole visible light range (a property which could be used for the production of solar fuels), could make possible photovoltaic cells of improved efficiency.

Cr incorporation in CuGaS2 chalcopyrite: A new intermediate‐band photovoltaic material with wide‐spectrum solar absorption

“…The signal reaches a flat plateau, and then a new steep increase reaches the second maximum B at 670 nm (1.85 eV), which indicates that the IB is partially filled, just as in the theoretical prediction. The observed absorption behavior is very similar to the reported IB semiconductor In 2 S 3 /V .…”

“…In previous work, several doped semiconductor materials with IB feature have been predicted by using first‐principles calculations . Most interestingly, the V‐doped spinel structure In 2 S 3 as an IB material was synthesized based on the theoretical calculations . The experimental IB absorption feature was in accordance with the theoretical electronic structure.…”

Electronic band alignment at CuGaS2 chalcopyrite interfaces

“…The appropriate level of cationic substitution to form and intermediate band using transition metal atoms is about a 10%. At this level of metal concentration the main gap will be affected by less than one or two tenths of eV [37] so the band alignment should not change significantly.…”

Preparation of ZnS@In2S3 Core@shell Composite for Enhanced Photocatalytic Degradation of Gaseous o-Dichlorobenzene under Visible Light

“…The characteristics of band edges could lead to the reduction reactions more available. In spite of these advantages of In 2 S 3 , it is obvious that the strong light-etching phenomenon and low charge-migration efficiency would prevent it from practical applications as an individual component 20,21 . Thus, the coupling of In 2 S 3 with ZnS material for forming heterogeneous structures should be beneficial for effective separation and transfer of photo-induced carriers.…”