A series of multinary Cu‐In‐Zn‐Se‐S nanocrystals (NCs) are synthesized via a phosphine‐free and one‐pot approach, in which the Se powder and 1‐dodecanethiol (DDT) are used as chalcogenide sources, respectively. The X‐ray photoelectron spectra are used to confirm the presence of lattice sulfur in the as‐obtained products. The emission color and the relative photoluminescence quantum yields of the Cu‐In‐Zn‐Se‐S NCs can be tuned by varying the Cu contents, the amount of Se powder, as well as the DDT dosage. In addition, the formation process of the multinary Cu‐In‐Zn‐Se‐S NCs is different from that of quaternary Cu‐In‐Zn‐S NCs, which is dominated by the doping of Cu ions into the In‐deficient In‐Zn‐Se‐S NCs but not the partial interdiffusion of Zn2+ into the Cu‐based NCs. This plausible deduction is based on the comparison of optical properties of the products synthesized using the hot‐injection and one‐pot methods. Furthermore, the performance of the solution‐processed quantum‐dot light‐emitting diodes (QLEDs) using the Cu‐In‐Zn‐Se‐S NCs as emission layers is examined, and the QLEDs exhibit a high luminance over 1500 cd m−2 and a high peak current efficiency of ≈0.4 cd A−1 at 1000 cd m−2.
All-solution-processed red-emitting InP/ZnS-based QD-LEDs with a record ηEQE of 4.24% are successfully fabricated through the compositional engineering of colloidal ZnO NPs, which act as the electron transport layers.
Metallurgical
silicon was studied for photocatalytic H2 evolution activity.
It has been found that metallurgical silicon
with large particle size (above 800 nm) possesses poor photocatalytic
activity because of the deteriorating photoelectric performance of
the low-purity silicon. After size reduction (around 400 nm) and metal
nanoparticle decoration, the photocatalytic performance was significantly
enhanced to 1003.3 μmol·g–1·h–1. However, the photocatalytic performance of the Cu-,
Ag-, and Pt-decorated silicon is degraded with the increase of time.
Moreover, the degradation is independent of the metal. Electrochemical
test and X-ray photoelectron spectroscopy suggested that the Mott–Schottky
effect in the metal–silicon contact should be responsible for
the degradation. After forming a heterojunction by vulcanizing the
Ag-decorated silicon, the degradation was suppressed. Upgradation
of the metal–silicon contact to form a heterojunction was a
promising way to suppress the degradation and retain the high photocatalytic
performance.
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