This critical review reports recent advances in the development of metal–organic complexes for optoelectronic applications.

This review introduces the background, design and applications of paper-based supercapacitors, highlighting their importance for low-cost flexible energy storage.

Supercapacitors hold great promise for future electronic systems that are moving towards being flexible, portable, and highly integrated, due to their superior power density, stability and cycle lives. Printed electronics represents a paradigm shift in the manufacturing of supercapacitors in that it provides a whole range of simple, low-cost, time-saving, versatile and environmentally-friendly manufacturing technologies for supercapacitors with new and desirable structures (micro-, asymmetric, flexible, etc.), thus unleashing the full potential of supercapacitors for future electronics. In this review, we start by introducing the structural features of printed supercapacitors, followed by a summary of materials related to printed supercapacitors, including electrodes, electrolytes, current collectors and substrates; then the approaches to improve the performance of printed supercapacitors by tuning printing processes are discussed; next a summary of the recent developments of printed supercapacitors is given in terms of specific printing methods utilized; finally, challenges and future research opportunities of this exciting research direction are presented.

Lasing applications have spread over various aspects of human life. To meet the developing trends of the laser industry towards being miniature, portable, and highly integrated, new laser technologies are in urgent demand. Organic semiconductors are promising gain medium candidates for novel laser devices, due to their convenient processing techniques, ease of spectral and chemical tuning, low refractive indexes, mechanical flexibilities, and low thresholds, etc. organic solid-state lasers (OSSLs) open up a new horizon of simple, low-cost, time-saving, versatile and environmental-friendly manufacturing technologies for new and desirable laser structures (micro-, asymmetric, flexible, etc.) to unleash the full potential of semiconductor lasers for future electronics. Besides the development of optical feedback structures, the design and synthesis of robust organic gain media is critical as a vigorous aspect of OSSLs. Herein, we provide a comprehensive review of recent advances in organic gain materials, mainly focused on organic semiconductors for OSSLs. The significant breakthroughs toward electrical pumping of OSSLs are emphasized. Opportunities, challenges and future research directions for the design of organic gain media are also discussed.