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Inkjet printing as a thin film fabrication technique for Li-ion battery and perovskite solar cell applications

Prof. Dipti Gupta(, Ashok Kushwaha (PhD student, NCPRE-Energy storage group), Anu Teresa Peter (PhD student, NCPRE- Thin film materials & Devices group).

Inkjet printing is a versatile fabrication technique that can fabricate electronic devices in a digital non- contact mode that allows for printing on large areas and a variety of substrates with low wastage of materials, rendering it cost-effective, facile and scalable. Our group has developed inkjet printed micro porous thin film graphene electrode for high-performance lithium-ion battery, where printed electrode can retain 87% of initial reversible capacity after 100 cycles at high current density and reversible capacity of 942 mAh/g at 0.1C low current density. In this context, a thin-film Li-ion battery (LIB) system is being considered as a more suitable power supply since it has favorable features, such as being flexible, light weight, and thin, together with unparalleled high energy and power densities. More importantly, the reduced thickness of the electrodes helps with faster kinetics, leading to enhanced rate capability. However, fabrication of thin-film electrodes for LIBs is challenging and mostly relies on traditional thin- film deposition techniques, such as chemical vapor deposition (CVD), sputtering and pulsed laser deposition (PLD), and Sol–gel methods such as Dip/tape Casting and the Doctor Blade technique.

Unfortunately, many of these methods require expensive and sophisticated equipment(s), with necessities concerning attainment of a high vacuum and high temperature, which limit the development of thin-film batteries.

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Figure: (a,b) Inkjet-printed graphene thin films (c) FESEM image of printed graphene thin film (d) Variations of the reversible capacity and coulombic efficiency with cycle number for 100 cycles conducted at 2C current density. (e) Inkjet-printed triple cation perovskite thin films and the perovskite solar cells fabricated using inkjet-printed thin films. (f) Microfab Technologies, INC. Jetlab4 model Inkjet printer used for the thin film fabrications.

Perovskite solar cells (PSCs) rose to their current fame due to their rapid performance growth in a short period of one decade, as compared to silicon solar cells. Though they have achieved high performance using lab-scale techniques, their stability and scalability still remain a roadblock towards commercialization. Inkjet printing, an efficient and scalable method, can be applied to fabricate different functional layers of perovskite solar cells. As a benchmark for comparing inkjet-printed perovskite solar cells, the primary step was to develop PSCs using spin-coating techniques. We have achieved 14% and 8.35% efficiency with triple cation perovskite in n-i-p mesoscopic and planar architectures in nitrogen atmosphere, respectively. The inkjet-printed PSCs with triple cation perovskite fabricated in ambient condition with humidity greater than 80% reached efficiencies of 2.4% and 1.24% in n-i-p mesoscopic and planar architectures, respectively; which is under further optimization with respect to various parameters pertaining to inkjet printing.

Anu Teresa
Prof Dipti