The synthesis and characterization of low‐temperature solution‐processable monodispersed nickel cobaltite (NiCo₂O₄) nanoparticles (NPs) via a combustion synthesis is reported using tartaric acid as fuel and the performance as a hole transport layer (HTL) for perovskite solar cells (PVSCs) is demonstrated. NiCo₂O₄ is a p‐type semiconductor consisting of environmentally friendly, abundant elements and higher conductivity compared to NiO. It is shown that the combustion synthesis of spinel NiCo₂O₄ using tartaric acid as fuel can be used to control the NPs size and provide smooth, compact, and homogeneous functional HTLs processed by blade coating. Study of PVSCs with different NiCo₂O₄ thickness as HTL reveals a difference on hole extraction efficiency, and for 15 nm, optimized thickness enhanced hole carrier collection is achieved. As a result, p‐i‐n structure of PVSCs with 15 nm NiCo₂O₄ HTLs shows reliable performance and power conversion efficiency values in the range of 15.5% with negligible hysteresis.

We present the functionalization process of a conductive and transparent CuAlO2/Cu-O hole transporting layer (HTL). The CuAlO2/Cu-O powders were developed by flame spray pyrolysis and their stabilized dispersions were treated by sonication and centrifugation methods. We show that when the supernatant part of the treated CuAlO2/Cu-O dispersions is used for the development of CuAlO2/Cu-O HTLs the corresponding inverted perovskite–based solar cells show improved functionality and power conversion efficiency of up to 16.3% with negligible hysteresis effect.

Triisopropylsilylethynyl-pentacene (TIPS-PEN) has proven to be one of the most promising small molecules in the field of molecular electronics, due to its unique features in terms of stability, performance and ease of processing. Among a wide variety of well-established techniques for the deposition of TIPS-PEN, blade-metered methods have recently gained great interest towards the formation of uniform crystalline films over a large area. Following this rationale, we herein designed a versatile approach based on blade-coating, which overcomes the problem of anisotropic crystal formation by manipulating the solvent evaporation behaviour, in a way that brings about a preferential degree of crystal orientation. The applicability of this method was evaluated by fabricating field-effect transistors on glass as well as on silicon dioxide/silicon (SiO₂/Si) substrates. Interestingly, in an attempt to improve the rheological and wetting behaviour of the liquid films on the SiO₂/Si substrates, we introduced a polymeric interlayer of polystyrene (PS) or polymethylmethacrylate (PMMA) which concurrently acts as passivation and crystallization assisting layer. In this case, the synergistic effects of the highly-ordered crystalline structure and the oxide surface modification were thoroughly investigated. The overall performance of the fabricated devices revealed excellent electrical characteristics, with high saturation mobilities up to 0.72 cm² V⁻¹ s⁻¹ (on glass with polymeric dielectric), on/off current ratio >10⁴ and low threshold voltage values (<−5 V).