What question did this study set out to answer?

This research aims to explore how selenium composition affects the structure and performance of CdTe1−xSe x solar cells.

March 27, 2026Open Access

Bridging materials and devices: Selenium-driven bandgap and transport tuning in CdTe1−xSex solar cells

Key Points

This research aims to explore how selenium composition affects the structure and performance of CdTe1−xSe x solar cells.
Prepared CdTe1−xSex thin films across varying selenium compositions.
Utilized thermal evaporation for film deposition of ∼0.75 μm thickness.
Conducted X-ray diffraction and scanning electron microscopy analyses for structure assessment.
Performed optical measurements to evaluate band gap and absorption characteristics.
Measured electrical properties to assess carrier concentration and mobility.
Moderate selenium incorporation narrows the band gap and increases refractive index.
Optimal composition of CdTe0.6Se0.4 shows a balance of structure, optics, and transport.
Power conversion efficiencies reached 17.62% and 20.25% for different device configurations.
Increased carrier mobility and better resistivity enhance charge transport in selenium-rich films.

Abstract

Thin films of CdTe 1-x Se x were prepared and studied across the full selenium range to understand how composition shapes usefulness of the films as photovoltaic absorber layers. Using thermal evaporation to deposit ∼0.75 μm films, the structure evolves from CdTe-dominant cubic features to Se-rich mixed cubic–hexagonal phases as the selenium content x increases. This structure variation is accompanied by changes in grain texture and crystallinity seen by X-ray diffraction (XRD) and scanning electron microscope (SEM). Optical measurements show that moderate selenium incorporation narrows the band gap and raises the refractive index, which boost absorption without introducing excessive loss channels. Electrical tests indicate that this moderate selenium range of composition improves carrier concentration, mobility, and resistivity, supporting better charge transport. Among the alloys, CdTe 0.6 Se 0.4 achieves the best balance of structure, optics, and transport, and when integrated into n-CdS/p-CdTe and n-CdS/p-CdTe/CdTe 0.6 Se 0.4 devices, it delivers power conversion efficiencies of 17.62% and 20.25% under AM 1.5G, respectively. These findings demonstrate that the optimal selenium concentration in CdTe₁₋ₓSeₓ thin films is around x = 0.4, and the CdTe₀.₆Se₀.₄ composition stands out as a promising candidate for high-efficiency solar cell applications, which then offers a balance between structural stability, optical absorption, and electrical conductivity.

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