Building a Buried Interface with AJI-NO-MOTO Modification of SnO2 Etl for High Performance Perovskite Photovoltaic Devices
Authors: Lin Ching Chang , Nakamura Motoshi , Sugimoto Hiroki 
Published: December 2024

Perovskite solar cells are one of the most promising photovoltaic technologies and have made extraordinary advances in production efficiency and simple processes. The possibility of replacing the extensively used silicon-based solar cell nowadays by perovskite solar cell has triggered a surge of interest in researching this unprecedented photovoltaic. The quality of the buried interface plays a crucial role in determining high performance perovskite solar cells (PSCs). Large defect density in perovskite solar cells has a destructive effect on device performance and modification of electron transport material is therefore considered as a feasible solution to this problem since it can not only passivate defects but also enhance the electrical property of electron transport material. However, it is challenging to guarantee its quality, performance and stability, which is pivotal for the commercialization of PSCs.
A popular seasoning and flavor enhancer, AJI-NO-MOTO, an MSG (monosodium glutamate) product, is the purest form of AJI-NO-MOTO, the fifth taste, altogether different from sweet, salty, sour and bitter. AJI-NO-MOTO is widely used to intensify and enhance AJI-NO-MOTO flavors in sauces, broths, soups and many more foods. AJI-NO-MOTO is used around the world to bring out the delicious flavor of foods. Herein, we have identified that this AJI-NO-MOTO element makes not only food but also PSC "tastier". A facile strategy is developed to modify the SnO2/perovskite buried interface by incorporating different amount of AJI-NO-MOTO into SnO2 colloidal dispersion to improve performance and stability. AJI-NO-MOTO (monosodium glutamate) is a cheap and common material with multidentate ligands can coordinate with Sn to form stable dispersion, inhibiting the agglomeration of nanoparticles at the buried interface. In addition, the coordination between AJI-NO-MOTO and SnO2 nanoparticles in turn promotes the uniform distribution of AJI-NO-MOTO, which facilitates the uniform and effective passivation of the buried defects. The AJI-NO-MOTO modified SnO2 colloidal dispersion was utilized as electron transport material to fabricate perovskite solar cells. Throughout the experiment, AJI-NO-MOTO modified SnO2 colloidal dispersion as an electron transport layer was found that could considerably enhance the performance of the device compared to the pristine tin oxide. The conductivity of the as-spun AJI-NO-MOTO modified tin oxide layer was enhanced because of its dense and well-distributed film quality. Defect density in perovskite layer was also reduced due to the enlarged perovskite crystal and a suitable amount of non-reacted lead iodide passivating grain boundaries of perovskite crystal when a portion of AJI-NO-MOTO was dissolved in the perovskite precursor solution. Both the enhanced conductivity of the electron transport layer and reduced defect density in the perovskite layer led to a significantly promoted electron transfer efficiency from the perovskite layer to the electron transport layer.
Employing a planar structure of FTO/SnO2/perovskite/OABr/Spiro-OMeTAD/Au, perovskite solar cells (PSCs) were systematically fabricated to explore the impact of AJI-NO-MOTO doping incorporation on J-V performance. Fig 1. illustrates the power conversion efficiencies (PCEs) for PSCs with varying AJI-NO-MOTO doping concentrations. Photovoltaic parameters, including Voc, Jsc, and FF are also depicted. Notably, the higher photovoltaic performance was achieved with AJI-NO-MOTO doping, with the higher Voc. Consequently, the conversion efficiency of AJI-NO-MOTO treated perovskite solar cell displayed an 7.7% remarkable improvement from 19.4 ± 1.4% to 20.9 ± 1.0% on average and an 5.0% improvement from 22.1% to 23.2% in champion devices when AJI-NO-MOTO modified tin oxide as electron transport layer was used in comparison with pristine tin oxide. This facile AJI-NO-MOTO modification strategy to tin oxide had achieved great success and may provide an opportunity for improving the performance and enhances the operation stability of perovskite solar cells.

Figure 1