Citation: Chuchvaga, N.; Zholdybayev, K.; Aimaganbetov, K.; Zhantuarov, S.; Serikkanov, A. Development of Hetero-Junction Silicon Solar Cells with Intrinsic Thin Layer: A Review. Coatings 2023, 13, 796. https://doi.org/10.3390/ coatings13040796 Academic Editor: Alessandro Latini Received: 27 February 2023 Revised: 30 March 2023 Accepted: 17 April 2023 Published: 19 April 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). coatings Review Development of Hetero-Junction Silicon Solar Cells with Intrinsic Thin Layer: A Review Nikolay Chuchvaga * , Kairat Zholdybayev, Kazybek Aimaganbetov , Sultan Zhantuarov and Abay Serikkanov Institute of Physics and Technology, Satbayev University, Almaty A25A1G8, Kazakhstan * Correspondence: chuchvaga@sci.kz or nikolay.chuchvaga@gmail.com Abstract: This paper presents the history of the development of heterojunction silicon solar cells from the first studies of the amorphous silicon/crystalline silicon junction to the creation of HJT solar cells with novel structure and contact grid designs. In addition to explanation of the current advances in the field of research of this type of solar cells, the purpose of this paper is to show possible ways to improve the structure of the amorphous silicon/crystalline silicon-based solar cells for further improvement of the optical and electrical parameters of the devices by using of numerical simulation method and current hypotheses. This paper briefly describes the history, beginning from the first studies of and research of HJT-structure solar cells. It raises questions about the advantages and existing problems of optimization of HJT solar cells. The authors of this paper are proposing further ways of design development of HJT solar cells. Keywords: HIT; HJT; solar cell; quantum wall; modeling; review 1. Introduction The current challenges associated with the general growth of the world’s population, political, economic and environmental circumstances put before humanity the search for new solutions in the field of production, processing and consumption of world resources. One of the key solutions to this problem is the development of green energy. The concept of “green energy” means energy resources that do not harm the environment and are, therefore, meant as environmentally friendly resources. The development of this industry is associated with the development of more highly efficient technologies for energy pro- duction and energy consumption of resources, the search for new materials, the training of specialists and the creation of infrastructure and jobs, as well as the creation of favorable conditions for the development of the green energy market. One of the brightest and rapidly developing representatives is solar energy. This type of energy is associated with the conversion of solar energy, both for heat generation and with the use of semiconductor systems, for direct conversion of solar radiation into electricity. The main advantages of these systems are their efficiency, noiselessness, environmental friendliness and the ability to work in cloudy conditions and even in the rain. For the development of solar energy and its implementation in everyday life, there are tasks to increase efficiency, scale up production, search for new materials and, most importantly, reduce the cost of electricity produced. One of the most interesting materials capable of solving the presented problems is silicon. This is primarily due to the fact that silicon is the second most abundant chemical element on Earth. Despite the fact that silicon technology is the most traditional representative of solar energy, there are further technological ways to optimize the use of this material. One of the most prominent representatives of silicon technologies are silicon solar cells based on HIT and PERC technology. In recent years, HIT structure solar cells (heterojunction with thin intrinsic layer) or, as it is also called—HJT—have gained great popularity. Such a big interest in this design is related to high efficiency of devices, low-temperature production technology (up to Coatings 2023, 13, 796. https://doi.org/10.3390/coatings13040796 https://www.mdpi.com/journal/coatings