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.

Combinatorial experiments involve synthesis of sample libraries with lateral composition gradients requiring spatially-resolved characterization of structure and properties.Due to maturation of combinatorial methods and their successful application in many fields, the modern combinatorial laboratory produces diverse and complex data sets requiring advanced analysis and visualization techniques. In order to utilize these large arXiv:1904.07989v2 [cond-mat.mtrl-sci] 30 Apr 2019 data sets to uncover new knowledge, the combinatorial scientist must engage in data science. For data science tasks, most laboratories adopt common-purpose data management and visualization software. However, processing and cross-correlating data from various measurement tools is no small task for such generic programs. Here we describe COMBIgor, a purpose-built open-source software package written in the commercial Igor Pro environment, designed to offer a systematic approach to loading, storing, processing, and visualizing combinatorial data sets. It includes (1) methods for loading and storing data sets from combinatorial libraries, (2) routines for streamlined data processing, and (3) data analysis and visualization features to construct figures. Most importantly, COMBIgor is designed to be easily customized by a laboratory, group, or individual in order to integrate additional instruments and data-processing algorithms.Utilizing the capabilities of COMBIgor can significantly reduce the burden of data management on the combinatorial scientist.

Inorganic photochromic material is an available medium to obtain optical information storage. The photochromic property of the inorganic material is mainly from the defects of the host. However, the formation of defects in the host is uncontrollable, in particular, the revisable formation and removement of defects are difficult. Thus, there are few inorganic materials with the revisable photochromism upon the entire light stimulation. Therefore, it is an urgent need to find a suitable approach to design inorganic photochromic materials. Here, the photochromic PbWO 4 :Yb 3+ , Er 3+ ceramic was designed with the help of valence state change of W 6+ → W 5+ and Pb 2+ → Pb 4+ . Upon the 532 nm laser stimulation, the photochromism of the PbWO 4 :Yb 3+ , Er 3+ ceramic was obtained based on the Pb 2+ + hν (532 nm) → Pb 4+ + 2e − and W 6+ + e − + hν (532 nm) → W 5+ reaction, resulting in the optical information writing. Under the stimulation of an 808 nm laser, the written optical information was erased based on the W 5+ + hν (808 nm) → W 6+ + e − and Pb 4+ + 2e − + hν (808 nm) → Pb 2+ reaction. In addition, the photochromism-induced upconversion emission modification was obtained in the PbWO 4 :Yb 3+ , Er 3+ ceramic, realizing the effective and nondestructive reading out of optical information. The cyclic experiment demonstrated a good reproducibility of both photochromism and upconversion emission modification, exhibiting the potential application of the PbWO 4 :Yb 3+ , Er 3+ ceramic as the optical data storage medium.

Zinc tin nitride (ZnSnN2) is one of the emerging ternary nitride semiconductors considered for photovoltaic device applications due to its attractive and tunable material properties and earth abundance of constituent elements. Computational predictions of the material properties sparked experimental synthesis efforts, and currently there are a number of groups involved in ZnSnN2 research. In this article, we review the progress of research and development efforts in ZnSnN2 across the globe, and provide several highlights of accomplishments at the National Renewable Energy Laboratory (NREL). The interplay between computational predictions and experimental observations is discussed and exemplified by focusing on unintentional oxygen incorporation and the resulting changes in optical and electronic properties. The research progress over the past decade is summarized, and important future development directions are highlighted.

Optical data storage technology has many advantages over the traditional solid-state and magnetic storage technology, such as low cost, multi-dimensional storage, and rewritable capability. Therefore, the optical data storage technology has been in increasing demand for optical storage media. Herein, the photochromic and photoluminescence properties of BaMgSiO 4 :Bi 3+ ceramics were investigated. The BaMgSiO4:Bi3+ ceramics showed reversible photochromism from gray to pink upon alternating the 254 nm ultraviolet light and 532 nm laser irradiation. This is caused by the electron trapping and de-trapping in the oxygen vacancies of the BaMgSiO 4 :Bi 3+ host. This reversible behavior of photochromism was applied to fabricate different patterns on the surface of the BaMgSiO 4 :Bi 3+ ceramics, which exhibited the reversible dual-mode optical information recording and erasing abilities. The photoluminescence reversible modulation of the BaMgSiO 4 :Bi 3+ ceramics was obtained through the photochromic phenomenon. This modification behavior of luminescence could be applied to read-out the recording information in the BaMgSiO 4 :Bi 3+ ceramics. The coloration and bleaching of BaMgSiO 4 :Bi 3+ ceramics were dependent on the time of light stimulation, which facilitated multiplexing encoding. This photoluminescence and photochromism multiplexing of the BaMgSiO 4 :Bi 3+ ceramics enhanced the optical data storage capability.