Cadmium telluride (CdTe) thin-film solar cells are a type of thin-film solar cell based on a heterojunction of p-type CdTe and n-type CdS. CdTe thin-film solar cells are one of the fastest-growing photovoltaic devices among thin-film solar cells.
Advantages of cadmium telluride thin-film solar cells
1. Ideal bandgap: The bandgap of CdTe is generally 1.47 eV, and the spectral response of CdTe matches the solar spectrum very well.
2. High light absorption rate: The absorption coefficient of CdTe is as high as 104 cm-1 or more in the visible light range, and 95% of photons can be absorbed in a 1 μm thick absorption layer.
3. High conversion efficiency: The theoretical photoelectric conversion efficiency of cadmium telluride thin-film solar cells is about 28%.
4. Stable battery performance: The typical design life of cadmium telluride thin-film solar cells is 20 years.
5. Simple battery structure: low manufacturing cost, easy to achieve mass production.
Structure of cadmium telluride thin-film solar cells
Cadmium telluride thin-film solar cells are photovoltaic devices constructed by sequentially depositing multiple thin films on glass or other flexible substrates. A standard cadmium telluride thin-film solar cell typically consists of five layers:
1. Glass substrate: It mainly serves as a support for the battery, prevents contamination, and protects against incident sunlight.
2. TCO layer: also known as transparent conductive oxide layer. Its main functions are to allow light to pass through and conduct electricity.
3. CdS window layer: n-type semiconductor, forming a pn junction with p-type CdTe.
4. CdTe absorption layer: It is the main light-absorbing layer of the battery, and the pn junction formed with the n-type CdS window layer is the core part of the entire battery.
5. Back contact layer and back electrode: In order to reduce the contact barrier between CdTe and the metal electrode and draw out the current, the metal electrode and CdTe form an ohmic contact.
Preparation method of cadmium telluride thin-film solar cells
Cadmium telluride thin-film solar cells can be fabricated using various methods, such as chemical bath deposition (CBD), near-space sublimation, screen printing, sputtering, and evaporation. CBD is generally preferred for both industrial and laboratory applications because it is cost-effective and the generated CdS can form a good, dense contact with TCO.
