A 12 months after attaining what was a world document effectivity for a tandem perovskite-silicon photo voltaic cell on the time, scientists from EPFL and CSEM revealed a paper exhibiting the technical options of the system and the way the outcome was made potential. The bottom line is to control the perovskite crystallization course of utilizing an additive within the processing sequence.
the The Swiss Heart for Electronics and Microtechnology (CSEM) and the École polytechnique fédérale de Lausanne (EPFL) introduced in June 2022 that they’d achieved an influence conversion effectivity of 31.25% for a 1 cm2 tandem perovskite-silicon photo voltaic cell, which they are saying represents, on the time, a world document for a PV system of this kind.
The 2 scientific establishments, nonetheless, didn’t launch many particulars concerning the cell expertise and the way the brand new document was achieved. Now, greater than a 12 months later, they introduced the cell and associated manufacturing processes within the paper “Interface passivation for 31.25%-efficient perovskite/silicon tandem photo voltaic cells,” revealed final week. on Science.
“Our crew took a pioneering strategy by designing a tandem photo voltaic cell with a perovskite layer conformally coated on a silicon backside cell,” the lead writer of the analysis, Xin-Yu Chin, mentioned. pv journal. “The silicon backside cell has micrometric pyramids, an industry-standard innovation that enhances its photocurrent era.“
One of many key challenges in perovskite/silicon tandem cells is the recombination losses that happen on the perovskite high floor interfacing within the electron selective contact. Recombination is a course of through which photogenerated cost carriers – electrons and holes – recombine earlier than they are often collected and used to provide electrical energy, resulting in a lack of effectivity. “To deal with this situation, we included an additive within the processing sequence, which has confirmed instrumental in regulating the crystallization technique of perovskite,” defined Chin. “This step effectively passes the interface, which successfully reduces the recombination losses that hinder the general efficiency of the cell.”
The scientists used a phosphonic acid often called 2,3,4,5,6-Pentafluorobenzylphosphonic acid (FBPAc) to passivate the perovskite absorber and one other phosphonic acid known as methyl-substituted carbazole (Me-4PACz) to take away passivated interfacial defects within the gap transport layer (HTL).
The cell relies on a substrate product of glass and indium tin oxide (ITO), a Me-4PACz HTL, an absorber product of FABr:FAI perovskite with an power bandgap of 1.70 eV, a buckminsterfullerene (C60) electron transport layer, a bathocuproine (BCP) buffer layer, and a high electrode based mostly on copper (Cu).
Examined below normal lighting circumstances, the system confirmed an effectivity of 31.25%, an open-circuit voltage of 1.91 V, a short-circuit present of 20.47 mA/cm2, and a fill issue of 79.8%, all of that are licensed by the US Division of Power’s Nationwide Renewable Power Laboratory (NREL).
“The usage of Me-4PACz reduces the voltage loss on the perovskite / HTL interface, whereas the inclusion of FBPAc within the perovskite deposition sequence reduces the voltage loss on the perovskite / C 60 ETL interface and results in extra favorable perovskite microstructures with extra massive domains,” the researchers emphasised, including that the The outcome additionally exhibits that the expertise is able to advance to the subsequent stage of its improvement, which requires a central give attention to stability and scalability points.
“It’s potential that the expertise will take one other 5 to 10 years to enter the market. Present industrial options are already relevant to all thin-film supplies utilized in tandem photo voltaic cells, as demonstrated by the brand new Oxford PV outcomes,” added Chin. “The principle concern that the scientific neighborhood wants to deal with is the sturdiness of the perovskite materials. Can these supplies be sturdy sufficient to outlive for greater than 20 years in sensible functions? That is what issues. that query will decide the industrial success and affect of this expertise.”
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