Transparent conducting oxide (TCO) plays a crucial role in solar cells. These materials not only allow sunlight to penetrate the solar cell and be transformed into energy, but they also act as collectors for this converted energy. Transparent conductive oxides (TCOs) are materials that need to have two main properties: transparency, similar to glass, and conductivity, similar to metals.
TCO films are typically made with polycrystalline or amorphous microstructures and are applied to glass. Indium tin oxide is currently the industry standard for TCO due to its exceptional balance between optical transparency and electrical conductivity.
The dominant materials in the TCO market are aluminum-doped ZnO and tin-doped indium oxide. Due to its scarcity and high cost, indium is being actively researched to find better alternatives for Transparent Conducting Oxides (TCOs).
Applications of Transparent Conducting Oxide (TCO)
Transparent conducting oxides are extensively used in the design of various solar cells, including silicon heterojunction (SHJ) solar cells and perovskite-on-silicon tandem solar cells. Moreover, bifacial and semitransparent solar cells also make use of TCOs.
These TCO layers at the front of the solar cells serve as optically transparent electrodes. They allow photons to enter the solar cell and efficiently transport the photo-generated electrons to the terminals of external devices. Hence, it is essential for the front TCO of any solar cell device to have high lateral conductivity and low UV-IR absorption.
The cells that use high mobility TCOs demonstrate enhanced conversion efficiencies, thanks to their ability to generate higher current densities (Jsc) than standard ITO.
TCOs are also widely utilized in other areas such as display technology, low-emissivity windows, and electrochromic devices.
Also See: What is Solar Substrate?