Metal to Metal-Halide Perovskites. By Layla Khateeb, Aviv Dahari.

Solar Energy and Photovoltaic Technologies

Today, harnessing solar energy stands as a promising pathway toward achieving sustainability, underscored by the widespread adoption of solar energy solutions globally. Sustainable energy derived from solar photovoltaic (PV) technologies relies on materials that efficiently capture light, generating charge carriers that can be stored or utilized. While the developing of a functional PV device necessitates a synergy between various components like light absorbers, electron transport layers, and contacts, the principal limiting factor remains the light absorber itself. Undesired recombination processes in photo-generated charge carriers lead to losses in light-to-electron conversion efficiencies.

Challenges and Advances in Light Absorbers for PV Devices

Recently, the predominant light absorbers in high-efficiency PV devices, such as GaAs, Si, or CdTe, require costly purification and fabrication processes, hindering the widespread adoption of PV technologies and prompting a quest for alternatives. Recent years have seen scientists recognizing the superior material qualities of Halide Perovskites (HaPs) as potential replacements or enhancements to existing PV technologies at a lower cost. HaP-based solar cells have demonstrated electron-to-photon conversion efficiencies exceeding 25%, coming close to the efficiency of Si single-junction cells, the most commonly used light absorbers today. However, challenges such as toxicity, chemical stability, and manufacturing reproducibility have tempered the integration of HaP-based devices into the market. Notably, many high-efficiency HaP-based devices incorporate lead (Pb) in their composition, raising concerns about toxicity and the need for alternative materials.

Metal-to-Halide Perovskite (M2H) Conversion Method

The objective and driving force of our project is to understand the chemistry involved in converting precursor non-lead metals into Perovskites. This method, dubbed Metal-to-HaP (M2H) conversion, involves directly converting thin metal films into HaPs from a polyhalide-rich solution. The innovative aspect of this approach lies in its ability to control the oxidation state of the Pb-substituting elements, a challenge in achieving high-efficiency HaP structures. Moreover, the scalability and reduced toxicity of M2H conversion stem from the use of pure metal films as precursors, which are deposited using scalable processes and are less toxic compared to metal salts dissolved in organic solvents commonly used in current HaP fabrication methods.

Innovations in Metal-to-Halide Perovskite (M2H) Conversion and Alternative Materials

In our exploration of Metal-to-HaP (M2H) conversion, two metals stand out prominently: gold (Au) and copper (Cu). These metals offer distinct advantages that make them valuable candidates for use in HaP-based solar cells. Gold, renowned for its inertness and conductivity, plays a crucial role in facilitating the deposition process and ensuring uniformity in thin film formation. Its stability under various processing conditions makes it an ideal choice for creating precise interfaces within the perovskite structure, contributing to enhanced device performance and longevity.

On the other hand, copper, with its abundance and affordability, presents an attractive alternative to lead in HaP compositions. Copper-based perovskites have shown promising optoelectronic properties, including high absorption coefficients and carrier mobilities, making them well-suited for efficient light harvesting and charge transport in solar cells. Additionally, the use of copper can address concerns regarding the toxicity of lead, paving the way for more environmentally sustainable photovoltaic technologies.

By harnessing the unique properties of gold and copper in the Metal-to-HaP conversion process, we aim to not only advance the performance and scalability of HaP-based solar cells but also mitigate environmental and health risks associated with traditional lead-based formulations. This interdisciplinary approach, blending materials science with chemistry and engineering, holds great promise for revolutionizing the solar energy landscape, driving us closer to a future powered by clean and renewable sources.