Within the framework of green chemistry, solvents occupy a strategic place. To be qualified as a green medium, these solvents have to meet different criteria such as availability, non-toxicity, biodegradability, recyclability, flammability, and low price among others. Up to now, the number of available green solvents are rather limited. Here we wish to discuss a new family of ionic fluids, so-called Deep Eutectic Solvents (DES), that are now rapidly emerging in the current literature. A DES is a fluid generally composed of two or three cheap and safe components that are capable of self-association, often through hydrogen bond interactions, to form a eutectic mixture with a melting point lower than that of each individual component. DESs are generally liquid at temperatures lower than 100 °C. These DESs exhibit similar physico-chemical properties to the traditionally used ionic liquids, while being much cheaper and environmentally friendlier. Owing to these remarkable advantages, DESs are now of growing interest in many fields of research. In this review, we report the major contributions of DESs in catalysis, organic synthesis, dissolution and extraction processes, electrochemistry and material chemistry. All works discussed in this review aim at demonstrating that DESs not only allow the design of eco-efficient processes but also open a straightforward access to new chemicals and materials.

Deep eutectic solvents: syntheses, properties and applications

Interpretation of X-ray Powder Diffraction Patterns . By H. Lipson and H. Steeple. Pp. viii + 335 + 3 plates. (Mac-millan: London; St Martins Press: New York, May 1970.) £4.

X-Ray Diffraction

Solution-processed hybrid organic–inorganic perovskites (HOIPs) exhibit long electronic carrier diffusion lengths, high optical absorption coefficients and impressive photovoltaic device performance. Recent results allow us to compare and contrast HOIP charge-transport characteristics to those of III–V semiconductors — benchmarks of photovoltaic (and light-emitting and laser diode) performance. In this Review, we summarize what is known and unknown about charge transport in HOIPs, with particular emphasis on their advantages as photovoltaic materials. Experimental and theoretical findings are integrated into one narrative, in which we highlight the fundamental questions that need to be addressed regarding the charge-transport properties of these materials and suggest future research directions. The charge transport properties of hybrid organic—inorganic perovskites, which can explain their excellent photovoltaic performance, are reviewed through an integrated summary of experimental and theoretical findings. The potential origins of these properties are discussed and future research directions are indicated.

Hybrid organic—inorganic perovskites: low-cost semiconductors with intriguing charge-transport properties

Chalcopyrite thin film solar cells by electrodeposition

WS2/CdS photocatalysts with different amounts of WS2 cocatalyst are prepared by loading WS2 on CdS with an impregnation–sulfidation approach. The transformation process of the tungsten species loaded on CdS together with the junctions formed between WS2 and CdS are clearly demonstrated with X-ray photoelectron spectroscopy and transmission electron microscopy. Photocatalytic H2 production on WS2/CdS catalysts under visible light (λ > 420 nm) shows that WS2 cocatalyst plays a crucial role in H2 production. Under optimum conditions, the rate of H2 evolution can be increased by up to 28 times when CdS was loaded with only 1.0 wt % WS2, and WS2 demonstrates a catalytic performance comparable or even superior to those of noble metals. Photocatalytic reaction results and electrochemical measurements indicate that the significantly enhanced H2 evolution of WS2/CdS catalyst mainly owns to the junctions formed between WS2 and CdS and the excellent performance of WS2 as a cocatalyst in catalyzing H2 evolution.

Photocatalytic H2 Evolution on CdS Loaded with WS2 as Cocatalyst under Visible Light Irradiation

Electrodeposition of p–i–n type CuInSe2 multilayers for photovoltaic applications

https://repositorium.sdum.uminho.pt/bitstream/1822/27367/1/Nano-ilmenite%20FeTiO3-%20Synthesis%20and%20characterization.pdf

Nano-ilmenite FeTiO3 : synthesis and characterization

Making use of the authors' experimental results and the evidence available in the literature, an alternative model for glass/conducting glass/CdS/CdTe/metal solar cells has been formulated. This model explains the device behaviour in terms of a combination of a hetero-junction and a large Schottky barrier at the CdTe/metal interface. The main experimental observations available to date are described and compared with the currently assumed p–n junction model and this proposed new model. It is shown that the proposed model explains almost all the experimental results more satisfactorily. The paper describes the guidelines to further increase the performance efficiencies based on the new model. Following these new guidelines, the authors have fabricated improved devices producing open circuit voltage (Voc) values over 600 mV, fill factor (FF) values over 0.60 and the short-circuit current density (Jsc) values over 60 mA cm−2 for best devices. Although the Voc and FF could be further improved, the remarkable improvement of Jsc indicates the possibility of further development of multilayer graded band gap tandem solar cells based on CdS/CdTe system.

https://iopscience.iop.org/article/10.1088/0268-1242/17/12/306/pdf

Anura Priyajith Samantilleke

Papers

Electrodeposition of p–i–n type CuInSe2 multilayers for photovoltaic applications

Nano-ilmenite FeTiO3 : synthesis and characterization

New ways of developing glass/conducting glass/CdS/CdTe/metal thin-film solar cells based on a new model

Synthesis of cadmium and zinc semiconductor compounds from an ionic liquid containing choline chloride and urea

Investigation of electronic quality of chemical bath deposited cadmium sulphide layers used in thin film photovoltaic solar cells