| Work Detail |
An international team of researchers used a novel interfacial treatment to improve the performance of perovskite solar cells in a variety of narrow- and wide-bandwidth single-junction, tandem, and mini-module samples. An all-perovskite tandem solar cell demonstrated its use with a certified efficiency of 29.5%. An international research team led by Huazhong University of Science and Technology has successfully improved single-junction lead-tin (Sn-Pb) perovskite solar cells, as well as all-perovskite tandem and mini-module variants, using a novel interfacial engineering strategy based on a mercapto-functionalized scaffold. In the study, “ Mercapto-functionalized scaffold improves perovskite buried interfaces for tandem photovoltaics,” published in Nature Communications , the researchers describe how their approach enabled a single-junction narrow-bandgap (NBG) lead-tin perovskite solar cell with a power conversion efficiency of 23.7%, a two-terminal (2T) all-perovskite tandem solar cell with a certified efficiency of 29.5%, and 24.7% efficient mini-modules with dimensions of 5 × 5 cm². In stability tests, the modified solar cells consistently outperformed the control devices, according to the research. “The compatibility of our strategy across multiple architectures was very encouraging. We successfully applied it to narrow-bandgap lead-tin (Sn-Pb) perovskites, wide-bandgap (WBG) perovskites, and conventional bandgap perovskites,” corresponding author Zonghao Liu explained to pv magazine . “This universal interfacial engineering approach demonstrates significant potential for the scalability of perovskite solar modules.” To begin, the group identified nanovoids, or microscopic voids, at the buried interface between the PEDOT:PSS hole transport layer (HTL) and the narrow-band gap lead-tin perovskite as a critical factor degrading device performance, according to Liu. “To address this, we developed a mercapto-functionalized mesoporous silica scaffold strategy. This approach simultaneously modulates perovskite crystallization to eliminate nanovoids, suppresses tin(II) oxidation, passivates interfacial defects, and enhances charge extraction,” Liu said. The superscaffold was composed of mesoporous silica nanoparticles (MSNs) functionalized with (3-mercaptopropyl)trimethoxysilane (MPTS), which the researchers named MSN-SH. Several devices were demonstrated and characterized in the study. The NBG solar cells achieved an open-circuit voltage of up to 0.89 V and an efficiency of 23.7%. Additional tests were performed with the MSN-SH treatment on pure lead cells with bandgaps of 1.52 eV, 1.68 eV, and 1.77 eV and compared with control devices. The team found that the buried interface modification method was consistently effective. In particular, the 1.77 eV wide-band gap (WBG) solar cell achieved an efficiency of up to 20.6% at an open-circuit voltage of 1.33 V, in line with certified results. To further demonstrate the technology, a 2T all-perovskite monolithic tandem cell was fabricated. It achieved a certified efficiency of 29.50% and a maximum power point efficiency of 28.7%. The performance was certified by the Shanghai Institute of Microsystems and Information Technology in China. “Encouragingly, this is one of the highest performance values ??reported for all-perovskite, two-terminal monolithic tandems, to our knowledge,” the researchers noted. The all-perovskite tandem device stack was as follows: glass, indium tin oxide (ITO), methyl substituted carbazole (Me-4PACz) hole transport layer (HTL), WBG/MSN-SH perovskite absorber, 1,3-propanediamine dihydroiodide (PDAI2) passivation layer, buckminsterfullerene (C60) electron transport layer (ETL), bathocuproine (BCP) buffer layer, tin oxide (SnO), gold (Au) metal contact, PEDOT:PSS HTL, MSN-SH, NBG perovskite layer, ethylenediammonium diiodide (EDAI2) passivation layer, C60, BCP, and Ag. In thermal stability tests, the tandem device retained 82% of its initial efficiency after 150 h at 85°C, while the control devices retained “only 43% of their initial efficiency after 100 h,” the scientists reported. Furthermore, the MSN-SH-based device showed “promising” operational stability under MPPT conditions, retaining 93% of the initial efficiency after 450 h, which is better compared to 68% after 370 h for the control device. The tandem mini-modules were fabricated on 5 × 5 cm² glass substrates with a sub-cell width of 6.8 mm. Tests revealed an average efficiency of 24.2% and a peak value of 24.7%. The MSN-SH-encapsulated mini-module was also able to maintain more than 80% of its initial efficiency after more than 290 hours of continuous operation. The team noted that these results suggest “superior scalability potential for MSN-SH buried interface modification for multi-junction devices,” emphasizing that the design strategy provides “valuable insights for the community in developing functional superstructures that can precisely modulate the buried interface for solar cells and other optoelectronic devices.” Looking ahead, Liu noted that work will continue in this direction, investigating new functionalized nanoscaffolds, possibly using alternative ligand groups, with the goal of further optimizing charge transport and long-term operational stability. The group could also apply the strategy to other optoelectronic devices such as photodetectors and light-emitting diodes (LEDs). The research team included scientists from the Chinese Academy of Sciences, Huaneng Clean Energy Research Institute, East China University of Science and Technology, Shenzhen Polytechnic University, Southern University of Science and Technology, SUSTech Institute of Energy for Carbon Neutrality, Wuhan University of Technology, Optical Valley Laboratory, all in China, along with researchers from the University of Oxford in the UK and Kyoto University in Japan. |
