Copper sulfur compounds have always been the research focus owing to their excellent properties, which can be concluded into the following three aspects. Ⅰ. Copper and sulfur are rich in reserves, low in price, exerting little impact on the environment, and showing good biocompatibility. Ⅱ. Copper sulfur compounds are endowed with appropriate direct band gaps, plasmonic properties, high charge carrier concentrations and motilities. Ⅲ. The structural and stoichiometric diversity of copper sulfur compounds enable the fine-tuning of their properties. Accordingly, copper sulfur compounds play a significant role in various fields, such as photoelectric conversion, electronic and optoelectronic chip, medical treatment. Currently, researches on copper sulfur compounds mainly concentrate on tailoring their structure and morphology to realize the control of a single property, so as to optimize their performance for specific purpose. Unfortunately, the tuning processes are random in most cases, precise preparation according to special demand seems hard to achieve. Besides, existing researches primarily focus on the three dimensional nanocrystals, few research pay attention to copper sulfur compounds in low-dimension, despite most materials may exhibit better properties in low-dimension, which hinder the deep exploration of properties of copper sulfur compounds. In addition, it is also a research hot spot to combine copper sulfur compounds with other materials to achieve superior performance, and various Cu2-xS-based composites have been reported, yet the mechanism still remain confused. Moreover, researchers are still not familiar with non-stoichiometric copper sulfur compounds, therefore, it is an urgent issue to realize controllable preparation of these compounds with large area and high quality, and explore their structures as well as properties. The present research of copper sulfur compounds are highlighted by the morphology control of several stable phases. Various morphologies like nanorods, nanoparticles, nanowires, nanospheres, nanosheets, nanoplates, thin films and other unique morphologies have been achieved via the optimization of experimental technique and parameters, and their size can also be controlled in certain degree. The application research of Cu2-xS-based composites mainly lies in photoelectric batteries, counter electrode materials and energy storage batteries. The performance of these devices and materials are mainly enhanced by combing Cu2-xS and other sulfides, oxides, rGO, TiO2 or carbon materials. In recent years, computational materials science has revealed the idiographic view structure of Cu2-xS, and some properties related to the band structure have also been predicted, more charming properties of Cu2-xS remain unexplored. Yet the experimental verification and exploration are premised on the preparation of Cu2-xS with high quality. In this review, we summarize the existing researches on copper sulfur compounds, giving an expound of their structural configurations, preparation techniques, physical properties and applications. We hope that this review will offer some basic information concerning copper sulfur compounds and believe copper sulfur compounds will play an even bigger role in our real life. © 2019, Materials Review Magazine. All right reserved.
