Core-Shell Chalcogenides Quantum Dots for Efficient Cd(Se)Te Solar Cells

Cadmium telluride (CdTe)-based thin film solar cells are considered to be some of the most advanced photovoltaic technologies due to their low cost, stability, and power conversion efficiencies (PCEs). To improve performance, considerable resources have been poured into CdSeTe alloys with graded bandgap, ZnTe-based back contact, and group V doping strategies. Unfortunately, closing the efficiency gap with the SQL of~32% is still a major challenge, in part because of difficulty in forming a stable, low-resistance ohmic back contact. This difficulty stems from CdTe's high electron affinity (~4.3 eV) and deep valence band (~5.7 eV). Consequently, common metal electrodes (work function < 5 eV) introduce high energy barriers rather than ohmic behavior.

 

Prof. Feng Yan at Arizona State University has developed novel solution-processed Cd(S,Se)/ZnS core-shell quantum dots (QDs) as a multifunctional rear interface modifier for CdSeTe solar cells. This addresses back-contact challenges through improved valence-band alignment and surface defect passivation for efficient hole extraction and absorption. The wide-bandgap ZnS shell passivates surface defects, reduces recombination losses, and enhances chemical stability. When integrated with conventional Cu doping, the QD rear interface modifiers collectively boost power conversion efficiency exceeding 19% with improved circuit voltage and fill factor.

 

By enhancing back-contact performance and carrier extraction, these novel core-shell Cd(S,Se)/ZnS quantum dots improve CdSeTe thin-film solar cell efficiency and advance device performance.

 

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