Solar energy is an environmentally friendly alternative to conventional, non-renewable energy sources. However, current solar panels require the use of toxic materials as buffers, which is not sustainable. To this end, a team of scientists in Korea has developed a new environmentally friendly alternative called ZTO buffer that can overcome this limitation. This new advancement to make solar panels even more sustainable is indeed a cherry on top.
The imminent threat of the climate crisis is clear and, given the urgency, there is a need to accelerate the transition to renewables. In recent years, solar energy has become one of the most promising candidates for this job.
Now scientists from Incheon National University, Korea, explain their latest contribution in the field. Their results were published in a new study in Nano Energy and made available online on August 10, 2020 (before the final publication of the December 2020 edition).
Solar panels are made up of photovoltaic cells, whereby materials exposed to light create excited electrons, in other words: an electric current. Modern thin film solar cells are made up of micrometer or submicrometer thick layers of photovoltaic material so that they can be integrated into flexible, lightweight panels for use in a variety of substrates. However, this process has some limitations.
Prof. JunHo Kim, who led the study, explains, “Most thin film solar cells contain toxic and expensive elements that can hinder the expansion of solar cell applications.” Prof. Kim and his team are working to create a solar cell from naturally abundant, environmentally friendly materials that are easy to extract and inexpensive to manufacture.
The scientists examined environmentally friendly cells made from kesterite, a natural mineral that acts as a photon absorber. Most kesterite cells use a cadmium sulfide (CdS) buffer layer to optimize their performance. Despite their efficiency, the pollution associated with making these buffers and the toxicity of cadmium are not desirable features of an environmentally friendly solar cell.
To solve this problem, the researchers looked at a promising alternative, the “ZTO buffer”. In order to further improve the efficiency of the solar cell, the team aligned the energy levels of the electrons between the absorber layer (kesterite) and the buffer layer (ZTO).
This allowed for better circulation of electrons between the two layers, increasing the voltage and total power of the cell with a power conversion efficiency of 11.22%. To put things in perspective, current Kesterite cells that use CdS buffers have a maximum efficiency of 12.6%, which means that the proposed cell was highly efficient. This technique is the first to achieve such high performance using only environmentally friendly, abundant and inexpensive materials.
The importance of this research will only increase with the expected increase in the share of renewable energies in the next few decades. In view of the growing demand for solar modules, it is particularly important to obtain the components as environmentally friendly and inexpensive as possible. Dr. The technology described by Kim and his team brings us one step closer to that goal.
The research team’s vision for their invention is that of a renewable future. Prof. Kim closes with a discussion about the possible applications of their results: “Environmentally friendly thin-film solar cells could be installed on the roofs and walls of buildings and houses to generate electricity in our vicinity. They could also be used in ground vehicles (cars), buses and trucks) and sea transport (boats and long-distance ships) to partially support the electrical energy. “
Incheon National University
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