RESEARCH ARTICLE Facile preparation of high fluorescent carbon quantum dots from orange waste peels for nonlinear optical applications Pandiyan Surendran 1 | Arumugam Lakshmanan 1 | Gandhirajan Vinitha 2 | Gopal Ramalingam 3 | Pitchan Rameshkumar 1 1 PG and Research Department of Physics, Periyar E.V.R College (Autonomous), Tiruchirappalli‐620 023, Tamilnadu, India 2 Division of Physics, School of Advanced Science, VIT Chennai, Chennai, Tamilnadu, India 3 Department of Nanoscience and Technology, Alagappa University, Karaikudi, Tamilnadu, India Correspondence G. Ramalingam, Assistant Professor, Department of Nanoscience and Technology, Alagappa University, Karaikudi‐630 003. Tamilnadu, India Email: ramanloyola@gmail.com Funding information RUSA 2.0, Grant/Award Number: RUSA 2.0 grant No.F.24‐51/2014‐U, Policy (TNMulti‐; UGC‐NFHE, Grant/Award Number: UGC‐ NFHE (F117.1/201516/NFST201517STTA F117.1/201516/NFST201517STTAM1335; UGC‐RGNF, Grant/Award Number: F117.1/ 201617/RGNF201517SCTAM21802 Abstract A facile and eco‐friendly hydrothermal method was used to prepare carbon quantum dots (CQDs) using orange waste peels. The synthesized CQDs were well dispersed and the average diameter was 2.9 ± 0.5 nm. Functional group identification of the CQDs was confirmed by Fourier transform infrared spectrum analysis. Fluorescence properties of the synthesized CQDs exhibited blue emission. The fluorescence quantum yield of the CQDs was around 11.37% at an excitation wavelength of 330 nm. The higher order nonlinear optical properties were examined using a Z‐scan technique and a continuous wave laser that was operated at a wavelength of 532 nm. Results demonstrated that the synthesis of CQDs can be considered as promising for optical switching devices, bio‐scanning, and bio‐imaging for optoelec- tronic applications. KEYWORDS CQDs, fluorescence quantum yield, HR‐TEM, hydrothermal method, Z‐scan analysis 1 | INTRODUCTION Carbon dots are new promising carbonaceous materials that have attracted considerable attention in numerous research areas due to their unique physical properties. [1–4] In the ever‐expanding field of nanomaterial research, researchers are exploring new carbon source materials from natural sources that are simple, of low cost with high performance, and with the possibility of green synthesis a highly desir- able factor. [5–10] Recently, reports have detailed that organic mole- cules with an extended delocalized π‐electron system possess perfect nonlinear optical values. [11] Among various nonlinear optical materials, ‘green’ carbon source CDs have shown the maximum non- linear optical properties. Recent articles have demonstrated CQD syn- thesis using many natural materials and with an option to re‐use natural waste. [12–21] Orange waste peels are underused natural resources and it is still challenging to use these leftover residues effectively. For CQD synthesis, carbonization of glucose, sucrose, gly- col, glycerin, and citric acid has received significant attention. [22] Some previous reports have described the preparation and applica- tion of orange peel carbon dots as fluorescence markers, as bio‐ imaging agents, in photoluminescence, as efficient catalysts, and in energy sciences. [23–25] However, detailed reports for the nonlinear optical performance of CQDs is still absent and this article attempts to fill this gap. To the best of our knowledge, this article describes the first attempt to study third harmonic generation properties of CQDs prepared from orange peels. In this present work, we succeeded in CQD synthesis using orange waste peels as a carbon source via a hydrothermal method. The syn- thesized CQDs were characterized using high‐resolution transmission electron microscopy, Fourier transform infrared spectroscopy (FT‐IR), and powder X‐ray diffraction (PXRD) analysis. The linear optical prop- erties of the CQDs were examined over the ultraviolet (UV)–visible Received: 19 July 2019 Revised: 29 August 2019 Accepted: 1 September 2019 DOI: 10.1002/bio.3713 Luminescence. 2019;1–7. © 2019 John Wiley & Sons, Ltd. wileyonlinelibrary.com/journal/bio 1