Journal of Materials Chemistry C 

Abstract: Carbon quantum dots (CQDs, C-dots or CDs), which are generally small carbon nanoparticles (less than 10 nm in size) with various unique properties, have found wide use in more and more fields during the last few years. In this feature article, we describe the recent progress in the field of CQDs, focusing on their synthetic methods, size control, modification strategies, photoelectric properties, luminescent mechanism, and applications in biomedicine, optronics, catalysis and sensor issues.

Abstract: Graphene is highly desirable as an electromagnetic wave absorber because of its high dielectric loss and low density. Nevertheless, pure graphene is found to be non-magnetic and contributes to microwave energy absorption mostly because of its dielectric loss, and the electromagnetic parameters of pure graphene, which are out of balance, result in a bad impedance matching characteristic. In this paper, we report a facile solvothermal route to synthesize laminated magnetic graphene. The results show that there have been significant changes in the electromagnetic properties of magnetic graphene when compared with pure graphene. Especially the dielectric Cole–Cole semicircle suggests that there are Debye relaxation processes in the laminated magnetic graphene, which prove beneficial to enhance the dielectric loss. We also proposed an electromagnetic complementary theory to explain how laminated magnetic graphene, with the combined advantages of graphene and magnetic particles, helps to improve the standard of impedance matching for electromagnetic wave absorbing materials. Besides, microwave absorption properties indicate that the reflection loss of the as-prepared composite is below −10 dB (90% absorption) at 10.4–13.2 GHz with a coating layer thickness of 2.0 mm. This further confirms that the nanoscale surface modification of magnetic particles on graphene makes graphene-based composites have a certain research value in electromagnetic wave absorption.

Abstract: Since the development of the first white organic light-emitting device (OLED) in 1993, twenty years have passed. The power efficiency and lifetime of this white OLED were reportedly only <1 lm W−1 and <1 day, respectively. However, recent rapid advances in material chemistry have enabled the use of white OLEDs for general lighting. In 2012, white OLED panel efficiency has reached 90 lm W−1 at 1000 cd m−2, and a tandem white OLED panel has realized a lifetime of over 100 000 hours. What is more important in OLEDs is to shed clear light on the new design products, such as transparent lighting panels and luminescent wallpapers. These fascinating features enable OLEDs as a whole new invention of artificial lighting. In this review, we would like to overview the recent developments of white OLED, especially three key elemental technologies related to material chemistry: (1) low operating voltage technology, (2) phosphorescent OLED technology and (3) multi-photon emission (MPE) device technology.

Abstract: Twisted intramolecular charge transfer (TICT) is an electron transfer process that occurs upon photoexcitation in molecules that usually consist of a donor and acceptor part linked by a single bond. Following intramolecular twisting, the TICT state returns to the ground state either through red-shifted emission or by nonradiative relaxation. The emission properties are potentially environment-dependent, which makes TICT-based fluorophores ideal sensors for solvents, (micro)viscosity, and chemical species. Recently, several TICT-based materials have been discovered to become fluorescent upon aggregation. Furthermore, various recent studies in organic optoelectronics, non-linear optics and solar energy conversions utilised the concept of TICT to modulate the electronic-state mixing and coupling on charge transfer states. This review presents a compact overview of the latest developments in TICT research, from a materials chemistry point of view.

Abstract: We review the field of multinary metal chalcogenide nanocrystals, which has gained strongly increasing interest in the quest for novel narrow band gap semiconductors. Small (2–4 nm) CuInS2 and CuInSe2 nanocrystals, for example, exhibit size dependent luminescence in the visible and near infrared range. Their quantum yield can exceed 50% after growth of a ZnS shell, which makes them appealing emitters for lighting, displaying and biological imaging applications. Cu2ZnSnS4 (CZTS) nanocrystals, on the other hand, can be used as solution processed absorbing materials in thin film solar cells showing high power conversion efficiencies (currently around 8–10%). These examples illustrate that multinary metal chalcogenide nanocrystals have high potential for replacing classical cadmium and lead chalcogenide quantum dots in many fields. We give an overview of the chemical synthesis methods of the different systems reported to date, classifying them according to the obtained crystal structure. Next, we discuss their photophysical properties and give a brief description of the main fields of application. Finally, we conclude by outlining current challenges and related future directions of this exponentially growing domain.