The expanding market of photonic devices is ever-growing with a global size of 772 B$ (2021), which is well above the semiconductor market (555 B$ in 2021). LEDs and lighting, displays, telecom, sensors, and photovoltaics are the prominent applications. Nowadays, conventional optoelectronic device manufacturing requires physical and/or chemical thin film deposition techniques, which typically involve high vacuum and high-temperature processes. In addition, masking and photolithography are necessary to define the desired device geometry. In contrast to those conventional device manufacturing technologies, innovative fabrication approaches for optoelectronic devices based on solution processing methods such as inkjet printing (IJP) have gained great momentum.

Semiconductor material inks for lead halide perovskites (LHPs) and lately lead-free perovskites (LFPs) can be prepared to deposit a wide array of functional materials in the form of precursor inks or nanoparticle colloidal suspensions. IJP is a digital material deposition technology, which means that the desired material stack can be printed in any pattern with precision without the need for masks. It also allows great control of process parameters and is ideal for fast prototyping while having the potential for scalability. Consequently, mass scale and cost-effective production of optoelectronic devices is possible by leveraging the maturity of IJP.

We will review the recent advances on IJP of LHPs and LFPs for optoelectronic devices of our group (UB) in the framework of the Drop it (EU) project. We will first introduce the inkjet printing, the test, and optimization of LHPs layers like CsPbBr₃. Secondly, we will introduce the layers produced with suitable electron/hole transport and blocking properties and with stable interfaces with the inkjet printed perovskites. For the electron injection, we have POT2T, SnO₂, ZnO transport layers and LiF/Al electrodes. For the hole injection, we have PEDOT:PSS, NiO_x and ITO electrodes. We will show how by engineering the layer stack we are able to produce green LEDs from active layers of CsPbBr₃ with luminance up to 10⁴ nits. Thirdly, we will present a summary of our best results in printing LFPs. Particularly, high quality and high-performance Sn-based 3D and 2D perovskites like FASnI₃, TEA₂SnI₄ and PEA₂SnI₄, and other compositions based in In and Cu like Rb₃InCl₆:Sb, CsCu₂I₃ and Cs₃Cu₂I₅. Finally, we will show devices like solar cells, waveguides, photodetectors, and red LEDs fabricated by inkjet printing of those LFPs.