On July 13th Beijing time, the international academic journal Nature published a new breakthrough in photovoltaics from China online. Li Yongfang, academician of the Institute of Chemistry of the Chinese Academy of Sciences, and Meng Lei, a researcher team, put forward the strategy of "all stage regulation", which enabled the perovskite organic laminated solar cells to achieve the transformation from "fear of light" to "control of light", certified that the steady-state photoelectric conversion efficiency reached 28.04%, and set a new world record for the photoelectric conversion efficiency of such devices.
This new type of stacked solar cell, like layers of "spectral filters" of different colors, converts sunlight of different wavelengths into electrical energy through division of labor and cooperation, breaking through the theoretical efficiency limit of traditional single junction solar cells. It is as thin as paper, gentle and rollable. In the future, it can not only be attached to building glass and car skylights to generate electricity, but also provide lightweight energy for drones, wearable devices, and even space stations.
However, the iodine ions and bromide ions in the core material will "get angry" and clump together under light, leading to rapid performance degradation.
To this end, the research team ingeniously designed a "photo controlled" additive molecule called TDB (4- [3- (trifluoromethyl) -3H-bis [aziridin-3-yl] benzyl ammonium hydrochloride) to "fully regulate" the growth and operation of perovskite materials.
In the crystallization stage of material "birth", TDB molecules act like strict instructors, delaying the premature separation of different ions and allowing them to arrange uniformly, forming high-quality lattices. During the "working" stage of solar cells, TDB molecules enriched at grain boundaries are activated by light and transform into a strong "glue" TAB (4- (trifluoroacetyl) benzyl ammonium hydrochloride), firmly anchoring to the surface of perovskite and effectively inhibiting ion migration channels and phase separation.
The key technical challenge of this study is how to transform high bromine content wide bandgap perovskite from 'light sensitive' to 'light responsive', "said Meng Lei, a researcher at the Institute of Chemistry. This transition from 'fear of light' to 'control of light' is the core essence of the 'full stage regulation' strategy. ”
The perovskite organic stacked solar cell prepared by the team has been certified by a third-party organization, and the steady-state photoelectric conversion efficiency has reached 28.04%, breaking the world record for the efficiency of such devices. At the same time, the stability of the device has also been significantly improved, and it can still maintain 90% of its initial efficiency after 625 hours of continuous light operation.
Li Yongfang, academician of the CAS Member and researcher of the Institute of Chemistry, said that perovskite organic laminated solar cells have the advantages of light weight, flexibility and high specific power. They can be widely used in ground scenes such as buildings, transportation, wearable electronics, and can also play an active role in aerospace fields such as satellites, space stations, and deep space exploration. They are expected to provide a new scientific and technological path for further transformation of the energy structure and sustainable development of the earth.