Thin Film Deposition Techniques for Photovoltaic Devices: Thermal Evaporation versus Spin Coating

Abstract

This paper has critically discussed the two widely used thin-film deposition techniques which include thermal evaporation and spin coating and their merits and demerits as far as their capability to produce photovoltaic (PV) devices is concerned. When it comes to creating high purity of films, thermal vaporization under vacuum conditions has advantages in thermal evaporation [1]. Conversely, spin coating is characterized by the simplicity of operation, and the capacity to fabricate high quality films which may occur hence it finds application in laboratory research and small scale production projects [2]. The paper will focus on the methodology, materials used and end product of the films of each technique, their impact on device performance and the scalability of the devices in the solar energy solution. In particular, the thickness and uniformity of the films can be determined accurately by a physical vapor deposition method called thermal evaporation, which is particularly significant when dealing with large areas in industry [4], [5].

This method is adept at depositing multilayer structures and fast switching between layers, a vital characteristic to tandem solar cells, which frequently add layers of perovskites on various substrates including silicon [6]. Spin coating, on the other hand, is highly cost-effective and capable of using solution-processed materials and enables rapid screening of new material compositions and optimization of film properties to a variety of PV uses [7], [8]. The low-temperature processing capability has made this method especially desirable to reduce substrate oxidation and corrosion thereby enabling its use in a wide range of substrate materials such as insulators, semiconductors and metals [9]. Selection of these techniques is frequently determined by the material properties and the required film structure and the cost-effectiveness of large-scale manufacturing [10]. As an example, manufacturing of cadmium telluride thin films, which are commonly used as absorber layers, commonly involves thermal evaporation as it is effective in producing desired structural and electrical properties by controlling deposition [11]. On the other hand, perovskite solar cells, commonly explored due to their low-cost and high-efficiency, often use solution based processes, such as spin coating for their active layers [12].