Metal halide perovskite photovoltaics (MHP) faces fundamental challenges which hinder their tangible impact on the final applications, with performance and stability being critical limiting parameters. Adjusting the perovskite grain boundaries and the crystalline surface are the primary tools to overcome these issues. Additionally, the research in new selective transport materials also plays a key role in improving optoelectrical devices' stability and performance to their theoretical limit to extend the perovskite application range.

Beyond efficiency and stability issues, perovskite photovoltaics must rely on sustainable technology for a feasible and fast green transition. Sustainability simultaneously considers environmental, economic, and social dimensions. Any sustainable technology must: a) generate enough power with reduced space usage (efficiency), b) be cost-effective, and c) not be detrimental to the environment or society. The environmental impact of the device fabrication is seriously affected not only by harmful materials (heavy metals and solvents) but also by the energy consumption of the synthetic and deposition routes used at the laboratory scale, which are not realistic for scaled-up manufacturing. Therefore, developing low-demanding synthetic routes is compulsory for a fast green transition.

Here, we present the research already performed by our team towards the synthesis and passivation methods of device-oriented metal halide perovskites (monocrystals at the macro and nanoscale) and metal oxides as selective transport materials. Our synthetic routes are mainly based on the in-situ synthesis approach. This one-step, low-cost, and low-demanding approach offers the possibility of modifying the precursor solution formulation very easily to adapt them to commercial-available printing techniques, one of the reasons behind MHP's success. Regarding sustainability, the in-situ synthesis approach is a low-carbon footprint synthetic route compared to traditional wet chemistry and colloidal routes. Following the global tendency to develop solution-processed materials, we have been involved for years in the in-situ synthesis approach of different materials, from MHP [1,2] to metal oxides [3] and conducting polymers [4]. We will show our work with solution-processed MHP and transparent metal oxides formulated as precursor inks compatible with roll-to-roll printing for large-scale production. The working principle analysis, including electrical and optical techniques, displays how the optoelectrical response can be adjusted by controlling the crystal growth and synthesis conditions and surface passivation, which can be linked to fundamental variations in the surface and bulk structure and composition.

_{1. Low-demanding in situ crystallization method for tunable and stable perovskite nanoparticle thin films}

_{J. Noguera-Gómez, I. Fernández-Guillen, P. F. Betancur, V. S. Chirvony, P. P. Boix, R. Abargues.}

_{Matter. 2022, 5, 3541-3552}

_{https://doi.org/10.1016/j.matt.2022.07.017}

_{2. Spray-driven halide exchange in solid-state CsPbX3 nanocrystal films}

_{RI Sánchez-Alarcón, J Noguera-Gomez, VS Chirvony, H Pashaei Adl, Pablo P Boix, G Alarcón-Flores, JP Martínez-Pastor, R Abargues.}

_{Nanoscale. 2022, 14 (36), 13214-13226}

_{https://doi.org/10.1039/D2NR03262G}

_{3. Solution-processed Ni-based nanocomposite electrocatalysts: an approach to highly efficient electrochemical water splitting.}

_{J. Noguera-Gómez, M. García-Tecedor, J. F. Sánchez-Royo, L. M. Valencia Liñán, M. Herrera-Collado, S. I. Molina, R. Abargues, and S. Giménez.}

_{ACS Appl. Energy Mater. 2021, 4, 5255-5264}

_{https://doi.org/10.1021/acsaem.1c00776}

_{4. In Situ Synthesis of Polythiophene and Silver Nanoparticles within a PMMA Matrix: A Nanocomposite Approach to Thermoelectrics}

_{J F Serrano-Claumarchirant, A Seijas-Da Silva, J F Sanchez-Royo, M Culebras, A Cantarero, C M Gómez, R Abargues}

_{ACS Applied Energy Materials 2022, 5 (9), 11067-11076}