Unveiling the Design Rules for Tunable Emission in Graphene Quantum Dots - A High-Throughput TDDFT and Machine Learning Perspective

Aug 6, 2026

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Tailoring the optical properties of graphene quantum dots (GQDs) is essential for optoelectronics, bioimaging, and sensing, yet the combined effects of shape, size, and doping on emission are not fully established. This work performs a systematic high-throughput time-dependent density functional theory (TDDFT) coupled with machine learning over 284 GQDs spanning square, hexagonal, and amorphous geometries, sizes near 1–2 nm, and dopant configurations using B, N, O, S, and P at 1.5–7%. Results identify design principles linking dopant type, concentration, and geometry to emission wavelengths, including sulfur-doped cases yielding higher emission energies and visible-range emission. Mechanistic interpretation attributes trends to quantum confinement, symmetry breaking, and dopant-induced modifications, enabling practical emission-spectrum design rules for next-generation applications.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages32

Reading Time1 h 21 min

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Introduction

Motivation and fluorescence mechanisms

Prior experimental and TDDFT studies

Computational Details

arXiv :2408 .05594v2 [ cond-mat .mtrl-sci ] 19 Oct 2024 Unveiling the Design Rules for Tunable Emission in Graphene Quantum Dots: A High-Throughput TDDFT and Machine Learning Perspective Mustafa Coşkun Özdemir Department of Chemistry, İzmir Institute of Technology, İzmir, Türkiye Caner Ünlü Department of Chemistry, İstanbul Technical University, İstanbul, Türkiye Şener Özönder Institute for Data Science & Artificial Intelligence, Boğaziçi University, İstanbul, Türkiye ∗ The ability to tailor the optical properties of graphene quantum dots (GQDs) is critical for their application in optoelectronics, bioimaging and sensing. However, a comprehensive understanding of how shape, size and doping influence their emission properties remains elusive. In this study, we conduct a systematic high-throughput time-dependent density functional theory (TDDFT) and machine learning analysis of 284 distinct GQDs, varying in shape (square, hexagonal, amorphous), size ( ∼ 1–2 nm) and doping configurations with elements B, N, O, S and P at varying concentrations (1.5–7%) . Our findings reveal clear design principles for tuning emission wavelengths based on dopant type, concentration and GQD geometry. Notably, sulfur doping at specific concentrations consistently results in higher emission energies, with certain configurations yielding emissions within the visible range. By elucidating how quantum confinement effects, symmetry breaking and dopant-induced modifications govern GQD optical properties, we provide practical design rules for tailoring emission spectra for next-generation optoelectronic, bioimaging and sensing applications. ∗ Corresponding author: [sener.ozonder@bogazici.edu.tr](sener.ozonder@bogazici.edu.tr) 2 I. INTRODUCTION Graphene quantum dots (GQDs) are carbon-based 2D nanomaterials which consist of sp2 hybridized carbon atoms with lateral dimensions typically less than 10 nm, displaying unique electronic, optical and chemical properties due to quantum confinement and edge effects [1–6] . These carbon-based 2D nanomaterials exhibit exceptional photoluminescence, high surface area and biocompatibility, making them ideal candidates for various applications in bioimaging, sensing and optoelectronics [7–18] . GQDs have become center of attention in recent years due to their tunable fluorescence properties, which can be controlled by altering their size, shape, composition and functional groups, facilitating their use in advanced light-emitting devices, solar cells and photodetectors [7, 8] . Two primary pathways contribute to the fluorescence of GQDs: intrinsic state emission, which is associated with the sp2-hybridized carbon core and surface state emission, which is influenced by the surface chemical groups and carbon bonds [19] . The combination of surface defects, functional groups and heteroatom doping in the core of GQDs greatly affects their fluorescence properties [19] . Additionally, surface alterations like oxidation and reduction can adjust the colors of their emissions [19–21] . Experimental research on heteroatom doped graphene quantum dots has shown that doping distinct atoms to GDQs can control a variety of optical properties of the dots, including photoluminescence wavelength and quantum yield. The photophysical properties of GQDs undergo significant changes when doped with N and B atoms such as increasing their quantum yield and resulting in controllable shifts in their emission wavelength [22–24] . It was demonstrated that the photoluminescence of GQDs can be enhanced by doubly doping them with Mg and N [24] . It was also shown that doping GQDs with S, N and B resulted in red light emission [22] . In a separate recent study, doping GQDs with N and P or B can create dual emission spectrum [25, 26] . Enhanced photoluminescence, improved photostability and tailored electronic properties can be obtained with heteroatom-doped GQDs. These can in turn result in important breakthroughs in bioimaging,

FAQs

What problem does the study address about graphene quantum dots?

It targets the lack of a comprehensive understanding of how GQD shape, size, and heteroatom doping jointly determine emission properties.

How was the dataset for the analysis constructed?

The study analyzes 284 distinct GQDs using high-throughput TDDFT, varying geometry (square, hexagonal, amorphous), size (~1–2 nm), and doping type (B, N, O, S, P) across concentrations from 1.5% to 7%.

What key design rule is highlighted for tuning emission?

Emission wavelengths and energies can be tuned predictably by selecting dopant type and concentration together with GQD geometry; sulfur doping at specific concentrations yields consistently higher emission energies and can produce visible-range emission.

Aug 6, 2026

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