Developed by a analysis group in China, the two-terminal all-perovskite tandem system makes use of a 23.11%-efficient single-junction prime cell counting on an optimized Sn-Pb perovskite materials. The perovskite-perovskite cell was additionally in a position to retain 95.7% of the preliminary effectivity after being saved in a glovebox for two,200 h.
A gaggle of researchers led by the Wuhan College in China developed a two-terminal (2T) monolithic all-perovskite tandem photo voltaic cell that makes use of a tin-lead (Sn-Pb) perovskite materials for the highest cell.
The scientists defined that blended Sn-Pb perovskites have a slim bandgap (NBG) of roughly 1.26 eV, which makes them preferrred for environment friendly mild harvesting and current-matching with extensive bandgap (WBG) subcells in all-perovskite tandem cells.
“Nevertheless, NBG Sn-Pb perovskite photo voltaic cells present inferior effectivity and stability compared with their Pb-based counterparts due to the quick crystallization, which might result in nonuniform nucleation,” in addition they specified. “The speedy crystallization of Sn perovskites causes poor high quality of Sn-Pb perovskite movies, hindering the fabrication of environment friendly all-perovskite tandem cells and impeding their commercialization.”
The analysis group sought to handle this concern by gauging the mismatch in crystallization charges between Sn and Pb perovskites and modulating the grain progress and crystallization processes. It used, specifically, the N-(carboxypheny)guanidine hydrochloride (CPGCl) molecule, which is also called 4-guanidinobenzoic acid hydrochloride, to cut back defects and tin oxidation within the perovskite absorber of the underside cell.
“CPGCl molecules had been utilized as dopants at a mole ratio of 1% in Sn-Pb perovskite precursor options,” the lecturers harassed. “These molecules had a larger influence on the delay of crystallization and grain progress in Sn perovskites, leading to a delayed and balanced crystallization course of in Sn-Pb blended perovskites.”
The lecturers initially constructed the underside cell with an indium tin oxide (ITO) substrate, a gap transport layer (HTL) based mostly on PEDOT:PSS, the Sn-Pb perovskite absorber, an electron transport layer (ETL) based mostly on a buckminsterfullerene (C60), a bathocuproine (BCP) buffer layer, and a copper (Cu) metallic contact.
Picture: Wuhan College, scientific studies, Artistic Commons License CC BY 4.0
Examined underneath a reverse voltage scan, this cell achieved an influence conversion effectivity of 23.15%, an open-circuit voltage of 0.88 V, a short-circuit present density of 32.77 mA cm–2, and a fill issue of 80.11%. The system was additionally in a position to retain 97.45% of its unique effectivity after 3,500 h. “The improved system efficiency may be primarily attributed to the discount in service recombination,” the scientists stated. “Additional enhancements in system stability may contain the usage of stable encapsulation and steady cost transport layers.”
The analysis crew used then this cell to construct the perovskite-perovskite tandem system. The latter was constructed with an ITO substrate, a gap transport layer (HTL) manufactured from nickel(II) oxide (NiOx) and phosphonic acid known as methyl-substituted carbazole (Me-4PACz), a large bandgap (WBG) perovskite absorber, an ETL based mostly on C60, a tin oxide (SnOx) buffer layer, an HTL based mostly on PEDOT:PSS, the Sn-Pb perovskite absorber, an ETL based mostly on C60, a BCP buffer layer, and Cu metallic contact.
Examined underneath normal illumination circumstances, the tandem name reached a most effectivity of 28.20 and an authorized effectivity of 27.35%. It additionally achieved an open-circuit voltage of two.13 V, a short-circuit present density of 16.27 mA cm–2, and a fill issue of 78.94%. This system was additionally in a position to retain 95.7% of the preliminary effectivity after being saved in a glovebox for two,200 h.
The brand new photo voltaic cell idea was introduced within the paper “Combined tin-lead perovskites with balanced crystallization and oxidation barrier for all-perovskite tandem photo voltaic cells,” revealed in nature communications.
“Regardless of reaching excessive efficiencies in particular person subcells, the effectivity of all-perovskite tandem cells lags considerably behind their theoretical limits,” the researchers concluded. “To completely exploit the potential of high-efficiency subcells, analysis is required to develop steady interconnection layers that cut back each electrical and optical losses in tandem cells.”
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