Scientists in China built a four-terminal perovskiet-cigs tandem solar cell based on a top semi-transparent perovskiet device with an efficiency of 21.26% and a high bifaciality factor of 92.2%. They used a strategy for solvent gearbox to produce a perovskiet film with full coverage, larger grains, superior crystallinity and freedom of detectable lead-iodide-purity.
A group of researchers from Northwest Normal University in China has manufactured a four-terminal (4T) tandem solar cell based on a top semi-transparent perovskiet device and a soil cell that depends on copper-Indium-Gallium-selenide (CIGS).
“We used a step-by-step dimethyl sulfoxide (DMSO) solvent-anal method to improve the crystallinity of the perovskiet film used in the perovskiet top cell,” said the main author of the research, Yan Li, said PV -Magazine. “We have manufactured films with a wide band gap of 1.68 EV via two consecutive heating steps: glowing at 100 ° C and then 80 C.”
The scientists explained that the first step is intended to induce rapid nucleation and efficient growth of film grains with high crystallinity, while the second step is aimed at releasing DMSO molecules that prevent the sublimation of volatile organic halid species, so that lead (II (II (II (II ) Jodide is avoided ((ii) Jodide (PBI2) Growth of impurity phase.
Further electrochemical impedance spectroscopy (EIS) analysis showed that the step-by-step strategy for solvent-analysis was able to produce a perovskiet film with larger grains, higher crystallinity and purer phase than a control monster produced by the traditional solution-analysis method.
The research group built the upper perovskiet cell with a substrate made of Indiumtinoxide (ITO) and Glas, an electron transport layer (ETL) based on tinoxide (SNO2), the optimized perovskietbesorber, a spiro-timetad-transport layer (HTL)X) low and a semi-Transparent back contact made from indium zinc oxide (IZO).
This cell was able to achieve a power conversion efficiency of 21.26%, an open circuit voltage of 1,210 V, a short-circuit current density of 21.43 mA/cm2 and a filling factor of 0F 82.0%. It was then combined with a soil cigs solar cell with an efficiency of 18.29 %, whereby this efficiency value fell to 7.89 % after the lower device has been filtered by the semi-transparent perovskiet cell.
“The efficiency achieved in this is one of the highest values for 4-T PSC/CIGS Tandem solar cells that were reported earlier,” the research team emphasized and noted that the result was mainly due to the high efficiency of the top perovskiet cell And the high bifaciality factor of 92% reached through its semi-transparent IZO-Electrode.
The cell was described in the newspaper “A step-by-step strategy for solvent gearbox for very efficient four-terminal perovskiet/CU (INGA) SE2 Tandem solar cells“Published in Materials today energy.
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