Highly efficient, ultra-thin cadmium telluride thin-film solar cell technology connects to a green future.

Solar energy is considered an ideal resource for addressing current global energy challenges. As a virtually unlimited and environmentally friendly form of energy, it is becoming a key pillar of the global energy transition. Solar photovoltaic power generation is currently one of the most widely used methods of utilizing solar energy. Among various solar cell technologies, cadmium telluride (CdTe) thin-film solar cells, with their unique advantages of high efficiency, lightweight, stable performance, and low cost, are becoming a major thin-film photovoltaic product in the global photovoltaic market.

01 Structure and Working Principle of CdTe Power Generation Glass

The active layer of a CdTe thin-film solar cell is typically only a few microns thick, about one-tenth the diameter of a human hair. A typical cadmium telluride (CdTe) thin film solar cell consists of five layers:

(1) Glass substrate: It mainly acts as a support for the cell, preventing pollution and incident sunlight;

(2) TCO layer: It is a transparent conductive oxide layer, such as (SnO₂ or Cd₂SnO₂), which is transparent to visible light and has high conductivity and can efficiently transmit current;

(3) CdS window layer: It is a cadmium sulfide window layer, an n-type semiconductor, which forms a p-n junction with p-type CdTe. CdS is basically non-reactive for wavelengths above 520nm. Transparent, and allows the CdTe absorption layer to collect lower energy photons to generate electron-hole pairs under light;

(4) Cadmium telluride (CdTe) absorption layer: can achieve an optical absorption rate of more than 90% in less than 2μm thickness. Most carrier generation and collection occur here. The p-n 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, draw out the current, and make the metal electrode and CdTe form an ohmic contact. The back plate functions as sealing, insulation, and waterproof (generally made of TPT, TPE and other materials must be aging-resistant).

In addition, the complete CdTe power generation glass assembly also includes a junction box (protecting the entire power generation system and acting as a current transfer station) and an aluminum alloy protective laminate (playing a certain sealing and supporting role). Its specific working principle is that when sunlight shines on the surface of a cadmium telluride solar cell, the energy of the photon excites the electrons in the semiconductor, causing them to jump to the conduction band, while leaving a hole in the valence band, thus forming a photogenerated electron-hole pair. Due to the design of the cell structure, electrons and holes are guided to different areas for separation, with electrons being guided to the electron transport layer and holes being guided to the hole transport layer. Ultimately, the separated electrons and holes are guided to the electrodes, forming a current, thereby generating electrical energy.

02 How is cadmium telluride power generation glass manufactured?

The manufacturing process of cadmium telluride power generation glass components can be divided into four main steps:

(1) Material production: Cadmium and tellurium are by-products of zinc and copper mining operations, respectively. The waste generated by these mining processes has so far produced enough cadmium and tellurium, so no additional mining is required. The raw materials can be refined to produce pure cadmium and tellurium.

(2) Cell production: Cadmium telluride (CdTe) vapor is deposited on a coated conductive glass plate. After several rounds of laser scribing and material deposition and processing, the cell structure is finally formed.

(3) Module assembly: By adding electrical contacts to connect to other modules, adding edge sealants and a layer of encapsulant for weatherproofing, and finally the glass backplane, the completed cell is turned into a module assembly.

(4) Component deployment: The module is installed in the frame and connected to other module assemblies to produce green and clean electricity.

03 Application advantages of cadmium telluride power generation glass

The high efficiency and ultra-thin characteristics make cadmium telluride power generation glass components show great application potential in the field of building integrated photovoltaic (BIPV). They can be perfectly integrated into architectural design to achieve the unity of beauty and practicality. At the same time, cadmium telluride power generation glass has won wide recognition in the market for its high stability and low attenuation rate. Experimental data shows that the annual attenuation rate of cadmium telluride power generation glass is only 0.5%, which means that after 25 years, the component can still maintain more than 89% of the power generation capacity. Furthermore, CdTe solar glass exhibits excellent temperature coefficient and spectral efficiency, further enhancing its energy yield advantage by providing 4% more energy annually in hot climates and high humidity conditions.

In addition to high efficiency and stability, CdTe solar glass also offers numerous advantages, including strong low-light power generation capabilities, large product area, low temperature coefficient, minimal hot spot effect, and high safety performance. These advantages enable CdTe solar glass to maintain excellent power generation performance in a variety of climate conditions and installation environments, providing strong support for the widespread adoption of renewable energy.

While pursuing high efficiency and stability, CdTe thin-film solar cells also prioritize environmental protection and sustainable development. The main raw materials for CdTe photovoltaic modules are tellurium and cadmium, elements that are widely present in nature and can be recycled and reused sustainably. Furthermore, CdTe solar glass has a very low carbon footprint, 2.5 times lower than crystalline silicon modules over its lifecycle, and a water footprint three times lower, helping to reduce environmental pressure and promote green and low-carbon development.

Looking ahead, with the accelerated advancement of scientific research and industrial progress, cadmium telluride power generation glass will be applied and promoted in a wider range of fields. In the fields of building photovoltaic integration, household photovoltaic power stations, industrial and commercial buildings, and industrial manufacturing, CdTe thin-film batteries will play an important role and inject strong impetus into the development of green energy.