Information provided by Sofia Masi (Group of Advanced Semiconductors)

Perovskite solar cells are the most promising next generation photovoltaic technologies to produce solar energy with very high efficiency. Currently the main limitation is the low stability in ambient conditions of the core material of the device, the perovskite. A team of researchers, from UJI and INAM, has achieved excellent results by improving its stability and solar cell performances, while reducing the temperature processing, thanks to the use of lead sulfide quantum dots. The researchers fabricated perovskite solar cells with enhanced stability: the devices maintain their initial efficiency after 720 hours of testing in environmental conditions, thus approaching industrial stability standards. The research, published in ACS ENERGY LETTERS, is carried out within the European ERC Consolidator Grant.

Perovskite solar cells are made up of several layers: electron-hole pairs are generated in the photoactive layer of perovskite as a result of the sunlight absorption. Therefore, perovskite must be able to absorb as much solar energy as possible to be more efficient, that is, to have a low bandgap. Among the different perovskites, the most promising, the formamidinium lead iodide perovskite black phase, is also the least stable in air that quickly turns on a yellow non perovskite phase. It is here that the researchers intervened using lead sulfide semiconductor (PbS) quantum dots, as a material embedded in the perovskite absorber matrix.

The original approach used by UJI and INAM researchers exploits advanced devices fabrication and characterization techniques and theoretical calculations, for studying the mechanisms behind the improved stability of the active materials used in the devices. The greater stability of the material is due to the double beneficial role of PbS, on the one hand it promotes the growth of the photoactive crystalline phase of the perovskite and on the other the chemical bonds between perovskite and quantum dots stabilize it, phenomena that are not observed in cells free of PbS. The first effect benefits from the crystalline lattice parameters of the PbS, similar to those of the perovskite crystal, acting as a template for the growth of the perovskite crystal phase of interest. The second result is attributable to the stronger chemical bonds created between the PbS and the black phase, compared to those between the PbS and the yellow phase, which in fact inhibit the structural degradation of the perovskite itself.

This work also demonstrates the beneficial role of PbS in the perovskite solar cells scaling process: by fabricating cells with PbS, the temperature drops to 85 °C, significantly lower than that used for standard devices (150 °C).

These investigations pave the way for high-efficiency perovskite solar cells with stability that approach industry standards.

In clean energy technologies, the high efficiency, low cost and long life of the devices are crucial factors in achieving commercialization and widespread implementation. The use of perovskite in solar cells, promising for high photoactivity and light conversion efficiency, has a strong limitation: the efficiency degrades sharply in air, and this is currently the main obstacle to the commercialization of solar based technologies. This study shows that this limit could be overcome with a careful integration of quantum dots in solar cells, optimizing the amounts and the kinds of materials to be combined to produce efficient and stable perovskite solar cells.

Further information:
https://pubs.acs.org/doi/10.1021/acsenergylett.9b02450

Subscribe to Directory
Write an Article

Recent News

El diagnóstico genético neonatal mejor...

Un estudio con datos de los últimos 35 años, ind...

Más de 1.500 cambios epigenéticos en e...

Un equipo de investigadores de la Universidad Juli...

Tuneable reverse photochromes in the sol...

A new technique allows the design of solid materia...

Highlight

Eosinófilos. ¿Qué significa tener val...

by Labo'Life

​En nuestro post hablamos sobre este interesante tipo de célula del...

Un estudio de INCLIVA muestra el efecto ...

by INCLIVA

Han desarrollado un estudio para evaluar la correlación entre el teji...

Photos Stream