Wide band gap semiconductors are essential for today's electronic devices and energy applications due to their high optical transparency, as well as controllable carrier concentration and electrical conductivity. There are many categories of materials that can be defined as wide band gap semiconductors. The most intensively investigated are transparent conductive oxides (TCOs) such as tin-doped indium oxide (ITO) and amorphous In-Ga-Zn-O (IGZO) used in displays, carbides (e.g. SiC) and nitrides (e.g. GaN) used in power electronics, as well as emerging halides (e.g. g-CuI) and 2D electronic materials (e.g. graphene) used in various optoelectronic devices. Compared to these prominent materials families, chalcogen-based (Ch = S, Se, Te) wide band gap semiconductors are less heavily investigated but stand out due to their propensity for ptype doping, high mobilities, high valence band positions (i.e. low ionization potentials), and broad applications in electronic devices such as CdTe solar cells. This manuscript provides a review of wide band gap chalcogenide semiconductors. First, we outline general materials design parameters of high performing transparent conductors, as well as the theoretical and experimental underpinnings of the corresponding research methods. We proceed to summarize progress in wide band gap (E G > 2 eV) chalcogenide materials, such as II-VI MCh binaries, CuMCh 2 chalcopyrites, Cu 3 MCh 4 sulvanites, mixed anion layered CuMCh(O,F), and 2D materials, among others, and discuss computational predictions of potential new candidates in this family, highlighting their optical and electrical properties. We finally review applications of chalcogenide wide band gap semiconductors, e.g. photovoltaic and photoelectrochemical solar cells, transparent transistors, and light emitting diodes, that employ wide band gap chalcogenides as either an active or passive layer. By examining, categorizing, and discussing prospective directions in wide band gap chalcogenides, this review aims to inspire continued research on this emerging class of transparent conductors and to enable future innovations for optoelectronic devices.

A novel strategy of dehydrogenative Heck reaction controlled by redox process of ferrocene has been developed. Commercially available chiral amino acid as ligand realized asymmetric dehydrogenative Heck reaction, leading to planar-chiral ferrocene derivatives with excellent enantioselectivity and in good to excellent yields (up to 99% ee and 98% yield).Scheme 1 Palladium-catalyzed direct alkenylation of N,N-dimethylaminomethylferrocene.

Incorporating photosensitive molecules into the organic/inorganic hybrid materials can contribute to forming photoresponsive systems. The second/third-order nonlinear optical properties can be changed via external light stimulation at an appropriate wavelength. The photochromic metal complexes appear to be superior promising materials in the domain of photoswitchable nonlinear optics (NLO). Thus, the purpose of this review is to examine current progress of metal complexes in the field of photoswitchable NLO materials and provide perspectives for the future. The overview includes the second-order and third-order NLO photoswitches and NLO properties of metal complexes. Combined with the characteristics of pyrene and stilbazolium groups, we describe a new type of photoswitchable NLO materials. The rapidly increasing investigations in this domain suggest that NLO photoswitches of metal complexes would play a critical role for inspiring applications in the future.

Two novel Eu metal-organic frameworks (MOFs), namely {[Eu(pdba)(HO)]·2HO} (1) and {[Eu(pdba)(HO)]·5HO} (2), were prepared with 4'-(1H-pyrazol-3-yl)-[1,1'-biphenyl]-3,5-dicarboxylic acid (Hpdba) under hydrothermal conditions. MOF 1 exhibits a 3D supramolecular structure assembled from the ππ interactions between the benzene rings of the ligands, whereas 2 comprises a 3D structure through coordination connection between nitrogen atom and Eu. It is worth noting that the two MOFs showed good luminescence performance and high-sensitivity fluorescence quenching behavior toward Fe (Cr) and nitrobenzene. Furthermore, the experimental results for stability in water and cycle test show that these two MOFs can be used as potential fluorescent probes.

Eleven water-stable isostructural mono/bimetallic lanthanide coordination polymers (Ln-CPs) {[EuxTb1-x (HL)(H2O)3]·H2O}n (x = 1.0 (1), 0.9 (3), 0.8 (4), 0.7 (5), 0.6 (6), 0.4 (7), 0.3 (8), 0.2 (9), 0.1 (10), 0.05 (11), 0 (2), H4L = 5,5'-(1H-2,3,5-triazole-1,4-diyl)diisophthalic acid) with uncoordinated Lewis basic triazole sites within the pores were prepared. The Ln-CPs represented by 1 showed a rapid and drastic emission quenching induced by external Fe(3+) and Cr(3+) cations and CrO4(2-) and CO3(2-) anions in aqueous solution. In addition, because of the comparable emission intensities of Eu(3+) and Tb(3+) ions, bimetallic CP 8 can be used as a ratiometric luminescent sensor for organic solvent molecules. Moreover, the luminescent color of the 8 sensor in pyridine and in other guest solvents undergoes obvious changes that can be clearly distinguished by the naked eye.

Developing p-type transparent conductors (TCs) remains an outstanding challenge in optoelectronics and photovoltaics. This study uses combinatorial sputtering and spatially resolved characterization to map the full cation alloy space of Cu x Zn 1Àx S, a promising p-type TC. Formation of a metastable wurtzite alloy is observed between two cubic endpoints, leading to an electrical conductivity jump and onset of a wide-gap p-type semiconducting regime. These findings motivate further exploration of Cu x Zn 1Àx S, p-type TC development and continued application of the combinatorial materials discovery approach.

The wurtzite polymorph of MnTe with a wider band gap and moderate p-type doping is stabilized on an amorphous indium zinc oxide substrate.

Optically transparent materials with p-type electrical conductivity can facilitate the development of transparent electronics and improve the efficiency of photovoltaic solar cells. Sulfide materials represent an interesting alternative to oxides for these applications due to better hole transport properties. Here, transparent and conductive Ba–Cu–S thin films are prepared by combinatorial cosputtering and characterized for their composition, structure, and optoelectronic properties. The conductivity and transparency of these films are found to be strongly dependent on their chemical composition and the substrate temperature during growth. The conductivity of BaCu2S2 and BaCu4S3 can reach 53 S/cm (at 250 °C) and 74 S/cm (at 200 °C), respectively, which is higher than their solution processed/bulk counterparts. The 90% reflectance corrected transmittance is achieved in the wavelength range 600–1000 nm for BaCu2S2 and 650–1000 nm for BaCu4S3 (at 250 °C). These electrical and optical properties are comparable with other recently presented transparent p-type conductors, while the 200–350 °C processing temperature is low enough to be used in semiconductor devices with limited thermal budgets. Attempts have been made to synthesize the related Sr–Cu–S materials, following the theoretical suggestion of their potential as transparent p-type conductors, but these attempts resulted only in phase-separated SrS and Cu x S phases. Alloying BaCu2S2 with Sr on the Ba site on the other hand increases the conductivity to >100 S/cm while only slightly compromising the transparency of the material. To explain the difference between the Ba and the Sr containing copper sulfides, the lower bounds on the SrCu2S2 and SrCu4S3 formation enthalpies are estimated. While the doping of the Ba–Cu–S materials presented here is too large for application in transparent electronics, it is promising for potential use as p-type contact layers in thin film solar cells.