Groundbreaking study reveals how to make perovskite solar cells more practical than ever
The photovoltaic cells, which convert sunlight into electricity in most solar panels, are made of silicon. Solar cells comprising silicon crystals demand a lot of energy and are developed through costly multi-step manufacturing methods. This is why solar panels are currently so expensive.
However, there is an alternative to silicon that has the potential to reduce the cost as well as increase the efficiency of solar panels, according to a press release. We are talking about mixed-halide perovskites, special materials that can serve as ideal crystals for solar cells.
Perovskite solar cells (PSCs) were first invented in 2009, and since then, scientists have been trying to make them mainstream solar panel technology. However, PSCs and mixed-halide perovskite crystals are very unstable, and therefore, even after so many years of their discovery, the market is still dominated by silicon-solar cells (SSCs).
Looks like the time to shift from SSCs to PSCs has finally arrived. A team of researchers from the Swiss Federal Institute of Technology Lausanne (EPFL) has come up with a unique approach that could increase both the stability and efficiency of PSCs.
Making perovskite solar cells more feasible
The problem with mixed-halide perovskites is that they feature wide band gaps (the space between energy bands in a material). No electric activity happens in these gaps, and electrons can only move from one energy band to another if the band gaps are narrow.
On the other side, semiconductor material in solar cells is required to have smaller band gaps so that electrons excited by the sunlight can easily move to the conducting electrodes and generate electricity. Moreover, light from the sun can also cause the segregation of halides in mixed halide-perovskite.
This segregation further decreases the efficiency of a PSC while it is operational. According to the researchers, solar panels with cells having both perovskite and silicon (tandem solar cells) face these problems even with greater intensity.
"One of the obstacles on the way to commercializing perovskite solar cells is their operational stability, which puts them at a disadvantage compared to photovoltaic technologies already on the market. This is especially a problem with mixed-halide perovskites, which are ideal materials for tandem solar cells," the researchers explain.
The current study proposes an effective solution to overcome the limitations of PSCs. The authors claim to prevent the segregation of halides by treating PSCs with two alkylammonium modulators.
Two PSCs were tested using the proposed modulators non-stop for 1200 and 250 hours. The modulators were able to compensate for the energy losses from wide band gaps to the extent that the overall performance of the solar cells increased.
Their power-energy efficiencies witnessed a jump of nearly 25 percent and 21 percent, respectively, during the tests. The cell that went on for 1200 hours was even able to regain 90 percent of its initial efficiency (it was 80 percent for the other cell).
The modulators made metal-halide PSCs both stable (by preventing segregations) and energy efficient. This is a great achievement as it could further make PSCs more feasible than ever for both small and large-scale applications.
The study is published in the journal Joule.
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