Researchers have identified co-dopants that can enhance the photovoltaic performance of transparent metal oxides such as ZnO, In2O3 and SnO2, creating the potential for more efficient, powerful and stable solar cells. Solar cell technology has seen tremendous growth in recent years as a sustainable energy source. As energy generation and storage is a necessity these days, many efforts are being made worldwide to develop cost-effective options. Perovskites are a leading candidate to eventually replace silicon as the material of choice for solar panels. A perovskite solar cell consists of a perovskite layer as a light absorber, sandwiched between an electron transport layer (ETL) coated with transparent conductive glass and a hole transport layer (HTL) coated with a metal back contact electrode.
A research team from Alagappa University’s Department of Physics group focused on the electron transport layer of solar cell devices, which is made up of transparent metal oxides. Transparent metal oxides such as ZnO, In2O3 and SnO2 showed excellent electrical and optical properties. The team investigated the role that an effective dopant can play in improving the performance of tin oxide (SnO2) as an efficient transparent metal oxide for solar devices. SnO2 can be prepared at low temperatures and is relatively stable, but functional properties such as electrical conductivity, optical transparency, and band alignment with SnO2 perovskite are not sufficient to compete with commercial solar cells.
They found that while metallic aluminum (Al), when incorporated into the SnO2 lattice as a potential dopant, changed the electron concentration and series resistance of the film, the addition of metallic lanthanum (La) resulted in higher conductivity and an increased fill factor—the ratio of the maximum amount of power achievable. Accordingly, aluminum (Al) and lanthanum (La) metals were used as suitable dopants in SnO2 and improved the optical transparency, electrical conductivity, mobility, surface coverage and energy level of SnO2. It also greatly enhanced the photovoltaic performance, reproducibility and stability of the solar cell.
The surface coverage of the SnO2 film was increased by the addition of Al/La dopants, which enabled energy level modification and enhanced electron mobility, thereby improving the functional properties of SnO2 through simple metal ion doping strategies. This study, published in the Journal of Power Resources, shows the benefits of co-dopants in increasing photovoltaic performance, repeatability and stability in solar devices. The cross-sectional morphologies of the as-prepared perovskite films were analyzed using field emission scanning electron microscopy, while the elemental and chemical characteristics were investigated using X-ray photoelectron spectroscopy (XPS, Kratos AXIS Supra) supported by DST-Promotion of University Research and Scientific Excellence (PURSE). The study concluded that solar cells based on perovskite materials are cost-effective compared to commercial silicon-based solar cells.
