The synthesis of highly crystalline mesoporous materials is key to realizing high-performance chemical and biological sensors and optoelectronics. However, minimizing surface oxidation and enhancing the domain size without affecting the porous nanoarchitecture are daunting challenges. Herein, we report a hybrid technique that combines bottom-up electrochemical growth with top-down plasma treatment to produce mesoporous semiconductors with large crystalline domain sizes and excellent surface passivation. By passivating unsaturated bonds without incorporating any chemical or physical layers, these films show better stability and enhancement in the optoelectronic properties of mesoporous copper telluride (CuTe) with different pore diameters. These results provide exciting opportunities for the development of long-term, stable, and highperformance mesoporous semiconductor materials for future technologies.

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Bi2Se3 is a semiconductive material possessing a bandgap of 0.3 eV, and its unique band structure has paved the way for diverse applications. Herein, we demonstrate a robust platform for synthesizing mesoporous Bi2Se3 films with uniform pore sizes via electrodeposition. Block copolymer micelles act as soft templates in the electrolyte to create a 3D porous nanoarchitecture. By controlling the length of the block copolymer, the pore size is adjusted to 9 and 17 nm precisely. The nonporous Bi2Se3 film exhibits a tunneling current in a vertical direction of 52.0 nA, but upon introducing porosity (9 nm pores), the tunneling current increases significantly to 684.6 nA, suggesting that the conductivity of Bi2Se3 films is dependent on the pore structure and surface area. The abundant porous architecture exposes a larger surface area of Bi2Se3 to the surrounding air within the same volume, thereby augmenting its metallic properties.

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Major loss factors for photo-generated electrons due to the presence of surface defects in titanium dioxide (TiO2) were controlled by RF-sputtered tungsten trioxide (WO3) passivation. X-ray photoelectron spectroscopy assured the coating of WO3 on the TiO2 nanoparticle layer by showing Ti 2p, W 4f and O 1s characteristic peaks and were further confirmed by X-ray diffraction studies. The coating of WO3 on the TiO2 nanoparticle layer did not affect dye adsorption significantly. Dye sensitized solar cells (DSSCs) fabricated using WO3-coated TiO2 showed an enhancement of ~10% compared to DSSCs fabricated using pristine TiO2-based photo-electrodes. It is attributed to the WO3 passivation on TiO2 that creates an energy barrier which favored photo-electron injection by tunneling but blocked reverse electron recombination pathways towards holes available in highest occupied molecular orbital of the dye molecules. It was further evidenced that there is an optimum thickness (duration of coating) of WO3 to improve the DSSC performance and longer duration of WO3 suppressed photo-electron injection from dye to TiO2 as inferred from the detrimental effect in short circuit current density values. RF-sputtering yields pinhole-free, highly uniform and conformal coating of WO3 onto any area of interest, which can be considered for an effective surface passivation for nanostructured photovoltaic devices.