Pengyu Su

Controlled synthesis of nanotubes and nanowires decorated with TiO2 nanocuboids with exposed highly reactive (111) facets to produce enhanced photoelectrochemical properties

The ability to control the exposure of facets of a crystal has been garnering considerable attention due to the fascinating dependence of the physical properties of crystals on their shapes. Herein, a TiO2WT photoelectrode decorated with anatase TiO2 nanocuboids (TiO2C111WTs) displaying high-energy exposed (111) facets and quantum dot dimensions was prepared for the first time by using a TiCl4 treatment process. F− and NH4+ were introduced together to limit the randomness of the TiCl4 hydrolysates. We propose that both F− and NH4+ were necessary for controlling the exposure of the (111) facets. In comparison with TiO2WT photoelectrodes decorated with either randomly deposited TiO2 nanoparticles (non-facet) or with TiO2 nanofilms or with TiO2 nanocuboids displaying exposed {001} facets (denoted as TiO2PWT, TiO2FWT and TiO2C001WT photoelectrodes, respectively), the hybrid-structured TiO2C111WT photoelectrode achieved superior PEC performances, with Jsc and photoconversion efficiency values of 0.97 mA cm−2 and 0.49%. This enhancement was attributed to the exposure of the highly active (111) facets and the increased specific surface area of TiO2C111WTs. Meanwhile, the photoactive (111) facets offered oxygen vacancies, resulting in an increase of donor density and the enhancement of PEC performances. These facets also promoted the adsorption of CdS QDs and hence further sensitization. The CdS/TiO2C111WTs achieved Jsc and photoconversion efficiency values of 3.95 mA cm−2 and 2.05%, which were about twice those of CdS/TiO2WTs.

Enhanced photovoltaic properties of perovskite solar cells by TiO2 homogeneous hybrid structure

In this paper, we fabricated a TiO2 homogeneous hybrid structure for application in perovskite solar cells (PSCs) under ambient conditions. Under the standard air mass 1.5 global (AM 1.5G) illumination, PSCs based on homogeneous hybrid structure present a maximum power conversion efficiency of 5.39% which is higher than that of pure TiO2 nanosheets. The enhanced properties can be explained by the better contact of TiO2 nanosheets/nanoparticles with CH3NH3PbI3 and fewer pinholes in electron transport materials. The advent of such unique structure opens up new avenues for the future development of high-efficiency photovoltaic cells.

Synthesis of uniform cadmium sulphide thin film by the homogeneous precipitation method on cadmium telluride nanorods and its application in three-dimensional heterojunction flexible solar cells

High-density CdTe nanorod arrays are successfully embedded in a uniform and compact CdS layer, forming a novel three-dimensional (3D) CdTe NRs/CdS heterojunction structure. The CdS layer is prepared by homogeneous precipitation (HP) method using decomposition of urea. The effects of temperature and concentration of reactants on the growth and composition of CdS film are investigated in detail. The results demonstrate that the temperature affects the thermal decomposition of urea significantly, and the concentration of CdCl2 and CS (NH2)2 plays an essential role in the compositional ratio of CdS film. Further investigations reveal that, in comparison with the traditional precipitation method, a better coverage of CdS on the surface of CdTe NRs can be obtained by HP method due to the slow and even hydrolysis of urea. Moreover, photovoltaic performance of the novel CdTe NRs/CdS 3D photovoltaic device is also investigated. This study demonstrates that the 3D heterostructure has potential application in thin film solar cells, and the successful deposition of CdS layer on the surface of CdTe NRs by HP method suggests a promising technique for large-scale fabrication of these solar cells.

Enhanced photoelectric performance of CdS/CdSe co-sensitized TiO2 nanosheets array films

In this study, vertically aligned titanium dioxide nanosheets (TiO2NSs) array films were employed for the fabrication of photoanodes for quantum-dot sensitized solar cells (QDSSCs). The TiO2NSs array films were synthesized by a hydrothermal method. Then, cadmium sulfide (CdS) and cadmium selenide (CdSe) were assembled onto the TiO2NSs array films through chemical bath deposition (CBD) and successive ionic layer adsorption and reaction (SILAR), respectively. Detailed characterization measurements were carried out to analyse the crystallinity, microstructure, composition and optical properties of the samples. The CdS and CdSe QDs were densely and uniformly deposited on both {001} and {101} facets of the TiO2NSs array films. Moreover, the effect of CdS deposition time and number of CdSe deposition cycles (C) on the photoelectric performance was also investigated in detail. The best performance of 4.77% was achieved under AM 1.5 G illumination with Jsc = 18.22 mA cm−2, Voc = 0.51 V, and FF = 0.52 when the deposition time of CdS was 30 min and the deposition cycle of CdSe was 10C. The enhanced photoelectric performance mechanism of the co-sensitized device is also discussed in this paper.