3D Lifetime Tomography Reveals How CdCl₂ Improves Recombination Throughout CdTe Solar Cells

Area of Science:

• Materials Science
• Solid State Physics
• Photovoltaics

Background:

• Understanding carrier dynamics is crucial for improving photovoltaic device efficiency.
• Traditional optical techniques struggle to probe subsurface carrier behavior in polycrystalline films.

Purpose of the Study:

• To map carrier lifetimes in three dimensions within polycrystalline CdTe photovoltaic devices.
• To investigate the impact of cadmium chloride (CdCl2) treatment on subsurface carrier dynamics.

Main Methods:

• Utilized two-photon tomography to generate 3D maps of carrier lifetimes.
• Applied the technique to polycrystalline CdTe solar cells.

Main Results:

• Successfully mapped subsurface carrier dynamics, revealing information not accessible by conventional methods.
• Observed that CdCl2 treatment significantly enhances carrier lifetimes throughout the CdTe film.
• Identified substantial improvements in carrier lifetimes near subsurface grain boundaries and the buried p-n junction.

Conclusions:

• Two-photon tomography is a powerful tool for characterizing carrier dynamics in photovoltaic materials.
• CdCl2 treatment effectively suppresses nonradiative recombination in CdTe solar cells.
• Optimizing subsurface regions, particularly grain boundaries and the p-n junction, is key to enhancing CdTe solar cell performance.