An international research group has developed a solar cell based on a lead-free perovskite material known as Cs2AgBiBr6. The cell’s absorber was doped with trans-polyacetylene, which reportedly allowed the device to improve efficiency by more than 20%.
A group of researchers led by the University of Lahore in Pakistan has developed a solar cell based on an absorber made with a lead-free perovskite material known as Cs.2AgBiBr6.
The novelty of their approach consisted in doping the material with polyacetylene (PA). one of the most promising organic polymers for applications in optoelectronics. This doping process is intended to reduce the high energy band gap of the Cs2AgBiBr6. material, which the scientists indicated at 1.9 eV.
“The decrease in the energy gap is the result of adjusting the edges of the conduction and valence bands, while leading to an increase in electron injection from the perovskite layer to the electron transport layer,” they explained. “The increase in peak intensity clarified the crystallinity of the material.”
At the end of the doping process, the perovskite material had an energy band gap of 1.84 eV.
The team built the solar cell with a substrate made of glass and fluorine-doped tin oxide (FTO), an electron transport layer (ETL) that rests on a titanium oxide (TiO2), the perovskite absorber. hole transport layer (HTL) based on Spiro-OMeTAD and a gold (Au) metal contact.
The researchers tested the solar cell’s performance under standard lighting conditions and found that it achieved an energy conversion efficiency of 3.98%, an open-circuit voltage of 0.929 V and a short-circuit current density of 5.7 mA/cm.2and a fill factor of 75%. A reference device without doping achieved an efficiency of 3.29%, an open-circuit voltage of 0.920 V and a short-circuit current density of 5.13 mA/cm2and a fill factor of 69%.
“These improvements, together with the aforementioned bandgap improvement, could open promising avenues for the future commercialization of high-performance solar energy harvesting technologies,” the academics said.
They introduced the new cell concept in “Trans-polyacetylene doped Cs2AgBiBr6: Bandgap reduction for high-efficiency lead-free double perovskite solar cells”, which was recently published in Results in physics. “The study demonstrates the mechanical and dynamic stability of the Cs2AgBiBr6,they concluded.
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