Tuning the electronic and optical properties of hg-C$_3$N$_4$, quantum dots with edge-functionalization: A computational perspective

In this work, we have systematically investigated the structural, electronic, vibrational and optical properties of the edge-functionalized hg-C3N4 quantum dots with the aim of exploring their possible applications in solar cells and other optoelectronic devices such as light-emitting diodes. The functional groups considered in this work are methyl (-CH$_3$), fluorine (-F), and oxygenated groups such as aldehyde (-CHO), carboxyl (-COOH), ketone (-COCH$_3$), and hydroxyl (-OH) groups. The edge-functionalization resulted in significant tuning of the electronic, vibrational, and optical properties. Thus, their structural fingerprints are present in both their vibrational and optical properties, thereby allowing their detection both in the Raman as well as optical spectroscopies. It is observed that edge functionalization broadens the energy range of optical absorption, leading to coverage of most of the ultraviolet and visible regions. This implies that the edge-functionalization of hg-C$_3$N$_4$ quantum dots can be used in a variety of optoelectronic devices such as solar cells and light emitting diodes.