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Realization of high-performance optoelectronic and gaseous sensing with excellent mechanical flexibility may open up broad multifunctional applications, such as wearable smart sensor systems, robust environmental/infrastructure monitoring, and personal health monitoring...

During the chemical vapor deposition (CVD) of MoSe2, controlling its selenization reaction and understanding its reaction mechanisms are of great significance to obtain high‐quality 2D transition metal selenide semiconductors. Herein, a variable‐pressure CVD (VPCVD) method is reported to achieve the controllable transformation from MoO2 to MoSe2 monolayer based on gas pressure‐mediated selenization. At the gas pressure lower than 20 KPa, high‐temperature decomposition of MoO3 in the Ar/H2 mixture only produces MoO2 nanosheets without any selenization. When the gas pressure is between 20 and 60 KPa, quadrilateral MoO2 nanosheets are partially selenized. By further increasing the gas pressure from 60 to 100 KPa, they are completely selenized. At the downstream margins of as‐selenized films, 2D MoSe2 monolayers demonstrate a morphological evolution from triangle to hexagon and then to a continuous film. In addition, their Se vacancy concentrations and nucleation sizes depend directly on gas pressure. Therefore, the gas pressure‐mediated selenization provides a feasible way for the in situ synthetic control of chemical composition and vacancy doping of 2D transition metal selenides/oxides.

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Quantum dot-sensitized solar cells have gained rapid development which could produce potential applications. Although they have a theoretical photoelectric conversion efficiency of 44%, there is still a considerable gap in comparison with corresponding practical solar cells, which is mainly due to the fact that the interface transfer, stability and efficiency improvement are still facing some problems. In particular, the carrier recombination loss at the cell interface seriously hinders the quantum dot-sensitized solar cells from developing. In this work, an ultra-thin layer of InN prepared by plasma-enhanced atomic layer deposition is inserted into the FTO/TiO₂ interface of the photoanode of CdSeTe based quantum dot-sensitized solar cells to improve the performance of the photoanode structure, and physical mechanism behind the device is discussed. We first investigate the effects of different deposition temperatures (170, 200 and 230 ℃) on the cell performance of InN films. While the InN ultra-thin layer is deposited at 200 ℃, an enhancement of 16.9% in conversion efficiency is achieved as compared with the reference group. Then, the effects of different thickness (5, 10, and 15 cycles) on the cell are investigated at a fixed deposition temperature of 200 ℃. Additionally, an improvement of fill factor for the device after an introduction of InN layer is observed. This enhancement is further convinced by an apparent reduction of series resistance extracted by the Nyquist curve. The significant increase in fill factor indicates that the introduction of InN accelerates the extraction, transfer and separation of electrons, and reduces the possibility of photon-generated carriers recombination. However, the insertion of InN deposition temperature and thickness have a certain range of enhancement in the cell performance, and further investigation of the mechanism will be carried out.