Inkjet‐Printed Red‐Emitting Flexible LEDs Based on Sustainable Inks of Layered Tin Iodide Perovskite

Abstract

Abstract Inkjet printing has emerged as a promising technique for the fabrication of halide perovskite (HP) thin films, as it enables precise and controlled deposition of the perovskite ink on a variety of substrates. One main advantage of inkjet printing for the fabrication of HP thin films is its ability to produce uniform films with controlled thickness and high coverage, which is critical for achieving high‐performance devices. Additionally, inkjet printing allows for the deposition of patterned thin films, enabling the fabrication of complex device architectures such as light‐emitting diodes (LEDs). In this work, flexible LEDs based on inkjet printed Pb‐free HP thiophene‐ethylammonium tin iodide (TEA 2 SnI 4 ) are produced that has gained attention as a potential alternative to Pb‐based HPs in optoelectronic devices due to its lower toxicity, environmental impact, and high performance. The role of ink solutions is compared using pure solvents: toxic dimethyl formamide (DMF) and more eco‐friendly dimethyl sulfoxide (DMSO). Red‐emitting devices ( λ max = 633 nm) exhibit, in ambient conditions, a maximum external quantum efficiency ( EQE max ) of 0.5% with a related brightness of 21 cd m −2 at 54 mA cm −2 for DMSO‐based LEDs. The environmental impacts of films prepared with DMSO‐based solvents ensure only 40% of the impact caused by DMF.