Novel Physical Vapor Deposition Approach to Hybrid Perovskites: Growth of MAPbI3 Thin Films by RF-Magnetron Sputtering

Solution-based methods represent the most widespread approach used to deposit hybrid organic-inorganic perovskite films for low-cost but efficient solar cells. However, solution-process techniques offer limited control over film morphology and crystallinity, and most importantly do not allow sequential film deposition to produce perovskite-perovskite heterostructures. Here the successful deposition of CH3NH3PbI3 (MAPI) thin films by RF-magnetron sputtering is reported, an industry-tested method to grow large area devices with precisely controlled stoichiometry. MAPI films are grown starting from a single-target made of CH3NH3I (MAI) and PbI2. Films are single-phase, with a barely detectable content of unreacted PbI2, full surface coverage and thickness ranging from less than 200 nm to more than 3 {\mu}m. Light absorption and emission properties of the deposited films are comparable to as-grown solution-processed MAPI films. The development of vapor-phase deposition methods is of interest to advance perovskite photovoltaic devices with the possibility of fabricating perovskite multijunction solar cells or multicolor bright light-emitting devices in the whole visible spectrum

Stimulated and spontaneous four-wave mixing in silicon-on-insulator coupled photonic wire nano-cavities

We report on four-wave mixing in coupled photonic crystal nano-cavities on a silicon-on-insulator platform. Three photonic wire cavities are side-coupled to obtain three modes equally separated in energy. The structure is designed to be self-filtering, and we show that the pump is rejected by almost two orders of magnitudes. We study both the stimulated and the spontaneous four-wave mixing processes: owing to the small modal volume, we find that signal and idler photons are generated with a hundred-fold increase in efficiency as compared to silicon micro-ring resonators

Production of a green multi-purpose fuel by reactive distillation

Dimethyl ether (DME) is receiving growing attention as a promising alternative and multipurpose green fuel. World production today is primarily by means of methanol dehydration using solid acid catalysts in a fixed bed reactor followed by ordinary distillation columns. In this study, the continuous production via a single reactive distillation (RD) column is studied experimentally in a pilot-scale plant. Kinetics of liquid dehydration of methanol over the sulphonic resin Amberlyst 35 is also studied, using both a batch reactor and a tubular fixed-bed reactor in a temperature range of 100-140°C and a pressure up to 50 bar. The experimental kinetic data are described well by the Eley-Rideal mechanism, and the kinetic parameters are incorporated into a rate-based RD model implemented in the simulation environment Aspen Custom Modeler® (ACM®). The pilot-scale RD experimental results support the feasibility and benefits of the DME synthesis by RD process and are used to validate the predictive RD model. The validated model can be used for future sensitivity analyses and process optimization studies as well as benchmarking compared to the state of the art technology

Strong coupling between excitons in organic semiconductors and Bloch Surface Waves

We report on the strong coupling between the Bloch surface wave supported by an inorganic multilayer structure and $J$-aggregate excitons in an organic semiconductor. The dispersion curves of the resulting polariton modes are investigated by means of angle-resolved attenuated total reflection as well as photoluminescence experiments. The measured Rabi splitting is 290 meV. These results are in good agreement with those obtained from our theoretical model