The possibility of growing perovskite solar cells on flexible substrates can be seen as an exciting opportunity, allowing high throughput roll-to-roll manufacturing with a low embodied energy, and creating new applications in buildings, vehicles, portable electronics and internet-of-things based devices. Flexible perovskite solar cells have previously been developed on polymer substrates such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN) which are vulnerable to the ingress of moisture. Here we report the development of flexible perovskite solar cells grown on a typical transparent front sheet which is generally used to encapsulate flexible Cu(In,Ga)Se₂ (CIGS) solar cells. This type of substrate displays an ultra-low water vapor transmission rate and good UV blocking properties. Perovskite solar cells, grown on such flexible front sheets coated with a highly transparent conducting ZnO:Al (AZO) electrode and vacuum processed ZnO/C60 electron transport multilayer, yield 13.2% and 10.9% stabilized efficiencies for areas of 0.15 cm² and 1.03 cm², respectively. The substitution of an opaque rear contact with the transparent electrode enables the realization of flexible NIR-transparent perovskite solar cells with efficiencies above 12%. These devices display an average transmittance of 78% between 800 and 1000 nm and enable the development of 4-terminal polycrystalline all-thin-film flexible perovskite/CIGS tandem devices. In a first proof of concept 18.2% efficiency is obtained.

Over the last two decades, thin film solar cell technology has made notable progress, presenting a competitive alternative to silicon-based solar counterparts. CIGS (CuIn_1−xGa_xSe₂) solar cells, leveraging the tunable optoelectronic properties of the CIGS absorber layer, currently stand out with the highest power conversion efficiency among second-generation solar cells. Various deposition techniques, such as co-evaporation using Cu, In, Ga, and Se elemental sources, the sequential selenization/Sulfurization of sputtered metallic precursors (Cu, In, and Ga), or non-vacuum methods involving the application of specialized inks onto a substrate followed by annealing, can be employed to form CIGS films as light absorbers. While co-evaporation demonstrates exceptional qualities in CIGS thin film production, challenges persist in controlling composition and scaling up the technology. On the other hand, magnetron sputtering techniques show promise in addressing these issues, with ongoing research emphasizing the adoption of simplified and safe manufacturing processes while maintaining high-quality CIGS film production. This review delves into the evolution of CIGS thin films for solar applications, specifically examining their development through physical vapor deposition methods including thermal evaporation and magnetron sputtering. The first section elucidates the structure and characteristics of CIGS-based solar cells, followed by an exploration of the challenges associated with employing solution-based deposition techniques for CIGS fabrication. The second part of this review focuses on the intricacies of controlling the properties of CIGS-absorbing materials deposited via various processes and the subsequent impact on energy conversion performance. This analysis extends to a detailed examination of the deposition processes involved in co-evaporation and magnetron sputtering, encompassing one-stage, two-stage, three-stage, one-step, and two-step methodologies. At the end, this review discusses the prospective next-generation strategies aimed at improving the performance of CIGS-based solar cells. This paper provides an overview of the present research state of CIGS solar cells, with an emphasis on deposition techniques, allowing for a better understanding of the relationship between CIGS thin film properties and solar cell efficiency. Thus, a roadmap for selecting the most appropriate deposition technique is created. By analyzing existing research, this review can assist researchers in this field in identifying gaps, which can then be used as inspiration for future research.

This paper explores the latest developments in physical vapor deposition (PVD) techniques for fabricating silicon-carbon (Si/C) based thin films as anodes of Lithium-Ion batteries (LiBs). Properties of Si/C based materials, such as high thermal stability, electrical conductivity and mechanical strength, have addressed the critical challenges associated with the use silicon as anode material for LiBs, including as volume expansion during lithiation, structural stability and electrode degradation.

In this study, we demonstrate that in addition to improving the crystallization of CsPbI₂Br films, the incorporation of Cl⁻ and hydroiodic acid in the precursor solution leads to the formation of films with high coverage and large grains size.