Recent advancements in synthesis and property control of graphene quantum dots for biomedical and optoelectronic applications

Being a novel and interesting zero-dimensional material of the carbon family, graphene quantum dots (GQDs) have been studied extensively in the last few years due to their exceptional and desirable optical, chemical, physical, electrical and biological characteristics. Such unique size-dependent properties exhibited by them are a reflection of combined structural characteristics of small graphene sheets, furnished with quantum confinement and edge effects, and help them to demonstrate versatile applications in biomedical and optoelectronic domains. In this review, we summarize various top-down and bottom-up synthetic procedures to prepare GQDs with ease. Following this, several strategies adopted by researchers such as heteroatom doping, functionalization and controlling the reaction parameters to regulate their structure and chemical behavior are also discussed. A concise summary of several recent advances in the areas of biomedical (bio-sensing, bio-imaging, drug delivery, anti-bacterial activity and photo-thermal/dynamic therapy) and optoelectronic (light emitting diodes and solar cells) applications of GQDs has also been presented. Finally, a brief discussion on existing challenges and future prospective of this exciting material has also been included.