Molecular design of TiO2 for gigantic red shift via sublattice substitution.

The effects of 3d transition metal doping in TiO2 phases have been simulated in detail. The results of modelling indicate that Mn has the biggest potential among 3d transition metals, for the reduction of energy gap and the introduction of effective intermediate bands to allow multi-band optical absorption. On the basis of theoretical formulation, we have incorporated considerable amount of Mn in nano-crystalline TiO2 materials. Mn doped samples demonstrate significant red shift in the optical absorption edge, with a secondary absorption edge corresponding to theoretically predicted intermediate bands/states. The gigantic red shift achievable in Mn-doped TiO2 is expected to extend the useful TiO2 functionalities well beyond the UV threshold via the optical absorption of both visible and infrared photon irradiance.

Sputtered Ga-Doped SnOx Electron Transport Layer for Large-Area All-Inorganic Perovskite Solar Cells.

The scalability processing of all functional layers in perovskite solar cells (PSCs) is one of the critical challenges in the commercialization of perovskite photovoltaic technology. In response to this issue, a large-area and high-quality gallium-doped tin oxide (Ga-SnOx) thin film is deposited by direct current magnetron sputtering and applied in CsPbBr3 all-inorganic PSCs as an electron transport layer (ETL). It is found that oxygen defects of SnOx can be remarkably offset by regulating oxygen flux and acceptor-like Ga doping level, resulting in higher carrier mobility and suitable energy level alignment, which is beneficial in accelerating electron extraction and suppressing charge recombination at the perovskite/ETL interface. At the optimal O2 flux (12 sccm) and Ga doping level (5%), the device based on sputtered Ga-SnOx ETL without any interface modification shows a power conversion efficiency (PCE) of 8.13%, which is significantly higher than that of undoped SnOx prepared by sputtering or spin coating. Furthermore, a PCE of 5.98% for a device with an active area of 1 cm2 is obtained, demonstrating great potential in fabricating efficient and stable large-area PSCs.

In situ investigation of bismuth nanoparticles formation by transmission electron microscope.

Bismuth (Bi) nanoparticles are prepared by using NaBi(MoO4)2 nanosheets in the beam of electrons emitted by transmission electron microscope. The formation and growth of Bi nanoparticles are investigated in situ. The sizes of Bi nanoparticles are confined within the range of 6-10nm by controlling irradiation time. It is also observed that once the diameter of nanoparticles is larger than 10nm, the Bi particles are stable as a result of the immobility of large nanoparticles. In addition, some nanoparticles on the edges form nanorods, which are explained as the result of a coalescence process, if the irradiation period is longer than 10min. The in situ research on Bi nanoparticles facilitates in-depth investigations of the physicochemical behavior and provides more potential applications in various fields such as sensors, catalysts and optical devices.