Self-assembled monolayers (SAMs) are widely used as hole transport materials in inverted perovskite solar cells, offering low parasitic absorption and suitability for semitransparent and tandem solar cells. While SAMs have shown to be promising in small-area devices (≤1 cm²), their application in larger areas has been limited by a lack of knowledge regarding alternative deposition methods beyond the common spin-coating approach. Here, we compare spin-coating and upscalable methods such as thermal evaporation and spray-coating for [2-(9H-carbazol-9-yl)ethyl]phosphonic acid (2PACz), one of the most common carbazole-based SAMs. The impact of these deposition methods on the device performance is investigated, revealing that the spray-coating technique yields higher device performance. Furthermore, our work provides guidelines for the deposition of SAM materials for the fabrication of perovskite solar modules. In addition, we provide an extensive characterization of 2PACz films focusing on thermal evaporation and spray-coating methods, which allow for thicker 2PACz deposition. It is found that the optimal 2PACz deposition conditions corresponding to the highest device performances do not always correlate with the monolayer characteristics.

All-inorganic α-CsPbBr_xI_3-x perovskites featuring nano-sized crystallites show great potential for pure-red light-emitting diode (LED) applications. Currently, the CsPbBr_xI_3-x LEDs based on nano-sized α-CsPbBr_xI_3-x crystallites have been fabricated mainly via the classical colloidal route including a tedious procedure of nanocrystal synthesis, purification, ligand or anion exchange, film casting, etc. With the usually adopted conventional LED device structure, only high turn-on voltages (> 2.7) have been achieved for CsPbBr_xI_3-x LEDs. Moreover, this mix-halide system may suffer from severe spectra-shift under bias. In this report, CsPbBr_xI_3-x thin films featuring nano-sized crystallites are prepared by incorporating multiple ammonium ligands in a one-step spin-coating route. The multiple ammonium ligands constrain the growth of CsPbBr_xI_3-x nanograins. Such CsPbBr_xI_3-x thin films benefit from quantum confinement. The corresponding CsPbBr_xI_3-x LEDs, adopting a conventional LED structure of indium-doped tin oxide (ITO)/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/CsPbBr_xI_3-x/[6,6]-phenyl C61 butyric acid methyl ester (PCBM)/ bathocuproine (BCP)/Al, emit pure-red color at Commission Internationale de l'éclairage (CIE) coordinates of (0.709, 0.290), (0.711, 0.289), etc., which represent the highest color-purity for reported pure-red perovskite LEDs and meet the Rec. 2020 requirement at CIE (0.708, 0.292) very well. The CsPbBr_xI_3-x LED shows a low turn-on voltage of 1.6 V, maximum external quantum efficiency of 8.94%, high luminance of 2,859 cd·m^-2, and good color stability under bias.