Cadmium Telluride Thin-Film Solar Cells

Cadmium telluride (CdTe) thin-film solar cells form one of the most commercially successful photovoltaic technologies, owing to CdTe’s near-ideal direct bandgap of around 1.45 eV and high optical absorption coefficient. Standard device architectures comprise a transparent conducting oxide-coated glass substrate, a cadmium sulfide (CdS) window layer, the polycrystalline CdTe absorber and a metallic back contact. A critical CdCl₂ post-deposition treatment induces grain growth, defect passivation and improved charge transport, driving record cell efficiencies above 22 % and module performances exceeding 19 %. Deposition methods such as close-spaced sublimation, vapour transport, sputtering and electrodeposition enable thin-film manufacture with reduced material use and low capital costs. Current research targets bandgap grading via chalcogen alloying, dopant engineering to elevate hole and electron densities, and recombination control at grain boundaries, all directed at closing the gap to theoretical efficiency limits while ensuring long-term operational stability.

Research from Nature Portfolio

Recent studies have applied spatially resolved photoluminescence to CdSeₓTe₁₋ₓ thin films, demonstrating that selenium incorporation both passivates grain-boundary defects to boost radiative efficiency and simultaneously introduces sub-bandgap defect states within grain interiors that constrain ultimate device performance. Foundational atom-probe tomography and transmission electron microscopy investigations of CdTeₓSe₁₋ₓ alloy layers in bandgap-graded cells have clarified how Se concentration and resulting zincblende versus wurtzite phase formation govern photoactive layer properties, guiding precise control of Se diffusion to enhance short-circuit current and overall conversion efficiency.

Cadmium Telluride Thin-Film Solar Cells publication trend

The graph below shows the total number of articles in cadmium telluride thin-film solar cells across all publications each year (not limited to Nature Index journals).

Technical terms

Thin-film solar cell: Photovoltaic device in which semiconductor absorber layers of one to a few micrometres convert sunlight to electricity.

Bandgap grading: Spatial variation of semiconductor bandgap within the absorber to optimise charge separation and minimise recombination.

Grain boundary: Interface between crystalline grains where defect states can act as non-radiative recombination centres.

Passivation: Chemical or thermal process that neutralises electronic defect states to reduce carrier recombination.

Post-deposition treatment: Thermal or chemical step, such as CdCl₂ activation, that enhances crystallinity, grain growth and electronic quality.

References

1. Achieving 21.4% Efficient CdSeTe/CdTe Solar Cells Using Highly Resistive Intrinsic ZnO Buffer Layers. Advanced Functional Materials (2023).
2. Spatially resolved photoluminescence analysis of the role of Se in CdSexTe1−x thin films. Nature Communications (2024).
3. Structural and compositional dependence of the CdTexSe1−x alloy layer photoactivity in CdTe-based solar cells. Nature Communications (2016).
4. Review of the CdCl2 Treatment Used in CdS/CdTe Thin Film Solar Cell Development and New Evidence towards Improved Understanding. Coatings (2014).
5. CdTe-Based Thin Film Solar Cells: Past, Present and Future. Energies (2021).
6. Recombination and bandgap engineering in CdSeTe/CdTe solar cells. APL Materials (2019).