Energy‐Efficient Solar Photochemistry with Luminescent Solar Concentrator Based Photomicroreactors

AIEgens in Solar Energy Utilization: Advances and Opportunities

Solar energy is the most abundant energy resource on earth. Unfortunately, only a very small portion of the solar radiation can be utilized by current light-harvesting materials, thus leading to the poor utilization efficiency of solar energy. In this regard, aggregation-induced emission luminogens (AIEgens) have demonstrated versatile properties that can enhance energy conversion and potentially revolutionize solar utilization systems. AIEgens with great processability can selectively absorb radiation across multiple spectral regions and transform solar energy into longer-wavelength light, heat, or alternative forms of energy. These processes can considerably enhance the solar energy utilization performance by either developing light-harvesting systems based on AIEgens or hybridizing modern light-harvesting systems with AIE technology. In this Perspective, based on material properties, we highlight different functions of AIEgens related to solar light utilization, including sunlight transformation, chemical conversion, and thermal conversion.

Infrared Efficiency and Ultraviolet Management of Red-Pigmented Polymethylmethacrylate Photoselective Greenhouse Films

Red-pigmented photoselective polymethylmethacrylate (PMMA) films were prepared by casting from polymer/chloroform solution. The films were doped with efficient red fluorescent perylene dyes specialized for plastic coloration, namely KREMER 94720 and KREMER 94739, which have excellent weathering stability and a high fluorescence quantum yield. The effect of the doping concentration was studied using the atomic force microscope (AFM), optical transmission, color measurement, time-resolved fluorescence, and Fourier transform infrared spectroscopy (FTIR). The obtained results suggested the potential usefulness for photoselective greenhouse cladding applications as the lowest doping concentration (10−5 wt%) displaying the UV-open effect, whereas the best UV-blocking and thermic effects were obtained for the highest doping concentration (10−1 wt).

Exploiting the upconversion luminescence, Lewis acid catalytic and photothermal properties of lanthanide-based nanomaterials for chemical and polymerization reactions

Lanthanide-based nanocrystals possess three unique physical properties that make them attractive for facilitating photoreactions, namely photon upconversion, Lewis acid catalytic activity and photothermal effect. When co-doped with suitable sensitizer and...

Development of an Off-Grid Solar-Powered Autonomous Chemical Mini-Plant for Producing Fine Chemicals

Photochemistry using inexhaustible solar energy is an eco-friendly way to produce fine chemicals outside the typical laboratory or chemical plant environment. However, variations in solar irradiation conditions and the need for an external energy source to power electronic components limits the accessibility of this approach. In this work, a chemical solar-driven "mini-plant" centred around a scaled-up luminescent solar concentrator photomicroreactor (LSC-PM) was built. To account for the variations in solar irradiance at ground level and passing clouds, a responsive control system was designed that rapidly adapts the flow rate of the reagents to the light received by the reaction channels. Supplying the plant with solar panels, integrated into the module by placing it behind the LSC to utilize the transmitted fraction of the solar irradiation, allowed this setup to be self-sufficient and fully operational off-grid. Such a system can shine in isolated environments and in a distributed manufacturing world, allowing to decentralize the production of fine chemicals.

Photon Upconversion for Photovoltaics and Photocatalysis: A Critical Review

Opportunities for enhancing solar energy harvesting using photon upconversion are reviewed. The increasing prominence of bifacial solar cells is an enabling factor for the implementation of upconversion, however, when the realistic constraints of current best-performing silicon devices are considered, many challenges remain before silicon photovoltaics operating under nonconcentrated sunlight can be enhanced via lanthanide-based upconversion. A photophysical model reveals that >1-2 orders of magnitude increase in the intermediate state lifetime, energy transfer rate, or generation rate would be needed before such solar upconversion could start to become efficient. Methods to increase the generation rate such as the use of cosensitizers to expand the absorption range and the use of plasmonics or photonic structures are reviewed. The opportunities and challenges for these approaches (or combinations thereof) to achieve efficient solar upconversion are discussed. The opportunity for enhancing the performance of technologies such as luminescent solar concentrators by combining upconversion together with micro-optics is also reviewed. Triplet-triplet annihilation-based upconversion is progressing steadily toward being relevant to lower-bandgap solar cells. Looking toward photocatalysis, photophysical modeling indicates that current blue-to-ultraviolet lanthanide upconversion systems are very inefficient. However, hope remains in this direction for organic upconversion enhancing the performance of visible-light-active photocatalysts.

Flow Photochemistry as a Tool in Organic Synthesis

Photochemical transformations of molecular building blocks have become an important and widely recognized research field in the past decade. Detailed and deep understanding of novel photochemical catalysts and reaction concepts with visible light as the energy source has enabled a broad application portfolio for synthetic organic chemistry. In parallel, continuous-flow chemistry and microreaction technology have become the basis for thinking and doing chemistry in a novel fashion with clear focus on improved process control for higher conversion and selectivity. As can be seen by the large number of scientific publications on flow photochemistry in the recent past, both research topics have found each other as exceptionally well-suited counterparts with high synergy by combining chemistry and technology. This review will give an overview on selected reaction classes, which represent important photochemical transformations in synthetic organic chemistry, and which benefit from mild and defined process conditions by the transfer from batch to continuous-flow mode.