Improving the operational stability of perovskite solar cells

• Hybrid perovskites are materials made from metal halide frameworks intermixed with natural cations.

They have brought in a great deal of passion in the field of solar energy because of their light-harvesting capacity integrated with a low cost of manufacturing, making perovskite solar cells (PSCs) prime candidates for changing current silicon-based devices. Perovskites likewise reveal great potential in a variety of applications that include LED lights, lasers, and also photodetectors.

One of the obstacles en route to commercializing perovskite solar cells is their functional stability, which puts them at a drawback compared to photovoltaic modern technologies currently on the marketplace. This is particularly a problem with mixed-halide perovskites, which are excellent products for tandem solar cells and also emission-tunable LEDs since they integrate high compositional adaptability with optoelectronic performance.

Mixed-halide perovskites also feature vast bandgaps, a residential or commercial property that impacts the power required for a solar product to produce electricity. Yet in many mixed-halide perovskites, light can cause a phenomenon called halide phase partition, where the components "de-mix" into areas of differing halide web content. This segregation can bring about considerable efficiency issues during the functional lifespan of a solar cell. Solving it is, as a result, critical for the success of perovskite modern technology, specifically for solar cells with a so-called tandem setup, where mixed-halide, broad bandgap perovskites are commonly used in combination with a 2nd low bandgap perovskite or a silicon cell.

A team of scientists at EPFL's School of Basic Sciences have currently developed an approach that enhances both, power conversion performance and also stability, of solar cells based upon pure iodide as well as mixed-halide perovskites, while likewise subduing halide phase segregation in the latter. The paper is released in Joule, as well as the study was performed by the teams of Professors Michael Grätzel as well as Ursula Rothlisberger at EPFL and also led by Dr. Essa A. Alharbi and also Dr. Lukas Pfeifer.

The method deals with PSCs with two alkylammonium halide modulators that function synergistically to boost solar cell performance. The modulators were used as passivators, substances utilized to minimize flaws in perovskites, which are otherwise advertising the aforementioned degradation pathways.

In this research study, the researchers were able to utilize both modulators to stop halide segregation and also thereby considerably decrease the drops in power-conversion effectiveness seen in long-lasting use PSCs.

The brand-new method caused power-conversion efficiencies of 24.9% for one perovskite structure (α-FAPbI3) and also 21.2% for the other (FA65MA35Pb( I65Br35) 3). Regarding 90% as well as 80% of the preliminary efficiencies were maintained after 1200 as well as 250 hours of constant operation, respectively. The authors write, "By dealing with the vital issue of stability, our results represent a vital step in the direction of huge scale sensible applications of PSCs."