Researchers in China have outlined a new surface engineering strategy to build cheap solar cells without a hole transport layer. The devices were treated with benzoylcholine halide to reduce non-radiative recombination and achieved remarkable efficiency and stability.
A group of scientists led by Beihang University in China has developed a carbon-based all-inorganic perovskite solar cell without the use of an expensive hole transport layer (HTL).
In the proposed cell architecture, the absence of the HTL, which prevents direct contact between the carbon electrode and the perovskite, is compensated by engineering the surface composition of the perovskite film. the carbon electrode provides a theoretical basis for the preparation of HTL-free CsPbI2Br-carbon-based all-inorganic perovskite solar cells,” the researchers said.
The researchers explained that chemical reactions can be used to modify the low-dimensional (LD) structure on a three-dimensional (3D) perovskite surface to improve crystallization quality. In particular, they used benzoylcholine halide (BzChX), which they claimed “effectively” passivates halogen vacancy defects on the film while reducing non-radiative recombination.
“At the same time, an LD/3D heterostructure is formed on the surface of the CsPbI2Br perovskite films modified by BzChI and BzChBr, which promote the arrangement of the gradient energy level between the perovskite films and the carbon electrode, they highlighted.
The team built the cell with a substrate made from tin oxide (FTO), an electron transport layer made of titanium oxide (TiO2)an absorber made from a perovskite material known as CsPbI3and a carbon electrode.
Tested under standard lighting conditions, the proposed cell achieved an energy conversion efficiency of 14.15%, an open-circuit voltage of 1.21 V, and a fill factor of 79.03%. For comparison: a reference cell without the benzoylcholine halide treatment achieved an efficiency of 12.29%, an open-circuit voltage of 1.20 V and a fill factor of 78.36%.
The academics also discovered that the cells were being treated benzoylcholine halideafter 120 s of steady-state output, they still retained more than 92.9% of their initial efficiency.
Their findings are available in the article “Low-dimensional/3D heterostructure increases the efficiency and stability of carbon-based CsPbI2Br perovskite solar cells”, published in Cell Reports Physical Science. “This work provides a feasible way to achieve simultaneous energy level optimization and defect passivation by constructing an LD/3D heterostructure for high-performance CsPbI2Br-based solar photovoltaics,” they stated.
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