Preface

Quantum dots (QDs) were first theoretically proposed by Alexander Efros in 1982, and the term came into widespread use in 1986, although nanoparticles of semiconductor QDs had already been theorized in the 1970s. The attributes of quantum dots have led to their use in a number of research areas such as QD light emitting diodes (LEDs), QD solar photovoltaics, and quantum computing (qubits), as well as bio- and food technologies. This book focuses on a range of important real-time applications for QDs.

The book is in three sections. Section 1 (Quantum Dots in Solar and Other Energy Sector) reviews important advances in QD-based solar energy systems. The introduction of semiconductor quantum dots into photoelectric material can be an important and effective way to increase the efficiency of photoelectric devices and photovoltaic cells. Chapter 2 reports efficient energy harvesting mechanisms. Chapter 3 discusses two performance-enhancing applications of carbon quantum dots (CQDs). In solar cells, CQDs have been used as active absorbing layers, electron-transporting layers (ETL), hole-transporting layers (HTL), donor/acceptor or dopant. In white LEDs, CQDs have been used as a phosphor material in the presence and absence of composite material to produce white emission. In Chapter 4, different types of nanomaterial synthesis using QD physical and chemical properties are discussed. The chapter also covers the structure and synthesis of PbS quantum-dot sensitized solar cells (QDSSCs) using simple, safe and chemical-free ultrasonication techniques and without a capping agent. Finally, Chapter 5 proposes a simple, cost-effective and efficient solar photovoltaic system.

Section 2 (Quantum Dots in Bio and Food Technology) reviews important advances in the application of QDs in the biomedical field. Chapter 6 examines bio-sensing, bio-imaging, drug loading capacity, targeted drug delivery, anti-stacking limit hostile to bacterial activity, photo-thermal treatment, and photodynamic treatment. In Chapter 7, surface modification of QDs for biosensor applications with high sensitivity and selectivity is discussed. QDs are ideal fluorescent labels for lateral flow assays (LFA) due to their unique optical properties and resistance to chemical and photo-degradation, and the prospects and challenges of QDs in LFA are reported in Chapter 8. Chapter 9 introduces in-vitro and in-vivo bio-imaging applications and synthesis, modification and cytotoxicity expression methods. The application of QDs in the food industry is discussed in Chapter 10. Quantum dot-based sensors have promising prospects for food analysis and water treatment as nanomembranes, nanosensors, and absorbent photocatalysts. The many benefits of QDs for food packaging, including improved mechanical properties, better thermal stability, increased water resistance, UV barrier properties, and antimicrobial and antioxidant activity, are reported in Chapter 10.

Section 3 (Quantum Dots in Other Important Applications) contains a further four chapters. Chapter 11 reports basic findings of a theoretical investigation of QD

scattering in monolayer molybdenum disulfide (MoS2) electron propagation wave plane in a circular quantum dot of MoS2, and the scattering efficiency, square modulus of the scattering coefficients, the radial component of the far-field scattered current, and electron density. In Chapter 12, the determination of Qubit entanglement in one-step double photoionization of a helium atom is reported. Chapter 13 reviews QLED applications of Photobiomodulation (PBM) as a photodynamic therapy in medicine and examines the quantum mechanics of Transcranial Photobiomodulation (tPBM) and its ability to affect electrophysiological activity. Chapter 14 focuses on the application of 3D technology in teaching the discipline of stereometry.

The aim of this book is to provide readers with a detailed overview of the most recent advances in the fascinating world of quantum dots, as well as to outline some possible future directions. The book is addressed to students and scientists working in the field of quantum dots and advanced technologies.

We would like to express our thanks to all the contributors to this book and our gratitude to Ms. Marica Novakovic for her valuable assistance and constant support during the writing and final preparation of the book.

> **Dr. Jagannathan Thirumalai** Department of Physics, Srinivasa Ramanujan Centre, SASTRA Deemed University, Kumbakonam, Tamil Nadu, India

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Section 1

Quantum Dots in Solar

and Other Energy Sector

Section 1
