European physicists have managed to uncover the mechanisms explaining why defects within the structures of several types of artificial analogs of the mineral perovskite, utilized in solar cell manufacturing, do not result in a decrease in their efficiency.
This breakthrough will enable the creation of even more efficient panels, according to a press release from the Institute of Science and Technology Austria (ISTA). The study’s authors noted that as far back as the early 2010s, physicists determined that “defective” perovskites based on lead and halogens possess the capacity to absorb light energy with an exceptionally high degree of efficiency.
Another benefit of these materials is their suitability for use in light-emitting diodes (LEDs) and X-ray detectors. They also exhibit non-standard quantum characteristics, including the ability to maintain quantum states at ambient temperatures.
Perovskites are flexible and lightweight semiconductor materials featuring atypical properties and structures. Their composition is analogous to the naturally occurring mineral perovskite, which is adept at capturing light and converting it into other energy forms, due to the arrangement of metal atom “cubes” and oxygen atom octahedra within its framework.
Even presently, power sources based on perovskites frequently surpass their silicon counterparts in quality. Their primary advantage lies in a higher operational efficiency, yet scientists were puzzled until recently by the reasons for this superior performance. The persistence of this efficiency despite a high concentration of internal defects and impurities in these materials also remained unexplained. Researchers have now unveiled a unique mechanism whereby these defects actually enhance, rather than diminish, the perovskites’ light absorption efficiency.
They conducted measurements of the optical characteristics and structure of lead- and bromine-based perovskites, confirming that structural imperfections within the perovskite crystals play a crucial role in the separation and long-distance transport of positive and negative charges. These defects impede the rapid recombination of electrons and “holes,” thereby allowing for the extraction of more energy from the absorbed light.
This discovery provides an explanation for numerous contradictory properties observed in this group of lead- and halogen-based perovskites over the last fifteen years. Furthermore, scientists now possess the ability to fine-tune their properties by manipulating the structure and characteristics of defects and impurities. As the physicists conclude, this will aid in developing even more efficient solar panels, sensors, and other devices based on these nature-mimicking materials.
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