The tandem device is based on a lower thin film heterojunction cell that can bend and an upper perovskiet cell that can be manufactured with a low temperature process to prevent damage. It achieved the highest efficiency that has ever been registered so far for a flexible perovskiet-silicon tandem solar cell.
Researchers from Tokyo City University have manufactured a flexible tandem solar cell based on a top semi-transparent reverse perovskiet cell and a flexible soil thin-film silicon heterojunction (HJT) PV device.
“Stable and flexible silicon hetero junctions can be manufactured by thinning silicon, making the production of lightweight and flexible solar cells suitable for various applications such as building-integrated photovoltaisies,” tells the corresponding author of the research, Ryosuke Ishikawa PV -Magazine.
For the dilution of the 21.1%-efficient soil cell, the research group used a technique that is known as POtassium hydroxide (KOH) etching, a wet chemical etching process that is used to create cavities in silicon. It was used to texture the cellwafer on the back Micro-structured and completed.
The scientists have also made a protective layer deposited from silicon nitride (Sinx) film on both sides of the waffle due to chemical vapor deposits (CVD). The wafer was then cut into square pieces of 5 cm and the Sinx film along the outer edges was removed using a laser.
The upper cell was manufactured with a self-assembled monolaag made from Meo-2Pacz, which is also known as [2-(3,6-Dimethoxy-9H-carbazol-9-yl)ethyl]Phosphonic acid, a glass substrate coated with indium tinoxide (ITO), a perovskietabsorber with an energy band gap of 1.68 EV, An electron transport layer (ETL) made from Buckminsterfullere (C60), A Tinoxide (SNO2), another ITO layer, An anti-reflective coating based on magnesium fluoride (MGF2) and a silver (AG) metal contact.
Tested under standard lighting conditions, the tandem cell achieved a power conversion efficiency of 26.5%, an open circuit voltage of 1.83 V, a short-circuit current density of 17.9 mA/cm2 and a filling factor of 81.%. According to the research group, this result is the highest efficiency ever registered for a flexible perovskiet-silicon tandem solar cell.
Looking out, the researchers said they are planning to improve the power in the lower cell with a more precise design of the back-reflection structure. “In order to further improve conversion efficiency, future research should be improved the current matching by applying bifacial hetero junction to the bottom cell,” she explains further.
“We also plan to perform detailed evaluations of the bending properties and sustainability of this tandem solar cell.”
The new cell concept was presented in “High efficient perovskiet/silicon tandem solar cells with flexibility“Published in Solar -rlll.
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