Performance optimization of high efficiency CdSeTe thin film solar cell with back-contact buffer layer using...

Area of Science:

• Materials Science
• Renewable Energy
• Semiconductor Physics

Background:

• Cadmium telluride (CdTe) thin film photovoltaics offer a promising route to low-cost electricity generation.
• The efficiency of CdTe solar cells is often limited by poor back electrode compatibility with the absorber layer.
• A back contact buffer (BCB) layer is crucial for improving charge transport at the interface.

Purpose of the Study:

• To investigate the performance enhancement of a CdSeTe solar cell using a p-type copper oxide (CuO) as a back contact buffer (BCB) layer.
• To analyze the electronic band structure at the CuO/CdSeTe interface and its effect on charge transport.
• To optimize parameters for achieving high power conversion efficiency (PCE) in CdSeTe solar cells.

Main Methods:

• Numerical simulations were employed to model a CdSeTe solar cell with an ITO/ZnO/MgZnO/CdSeTe/CuO/Pt structure.
• The band alignment at the CuO/CdSeTe interface was characterized, revealing a conduction band offset of -0.21 eV and a valence band offset of -0.15 eV.
• Key parameters including absorber thickness, carrier concentration, and defect density were optimized.

Main Results:

• The CuO BCB layer facilitated an Ohmic contact, expediting hole transport to the back electrode.
• The modified CdSeTe solar cell achieved a notable PCE of 27.04%.
• Optimized device parameters included an absorber thickness of 1400 nm, carrier concentration of 10^16/cm^3, and defect density of 10^14/cm^3, resulting in a V_oc of 1.03 V and J_sc of 29.8 mA/cm^2.

Conclusions:

• Employing a CuO BCB layer effectively addresses the back contact compatibility issue in CdSeTe solar cells.
• The engineered interface significantly enhances charge transport and overall device performance.
• This research provides a pathway for developing high-efficiency CdSeTe solar cells through strategic back contact engineering.