The integration of self-assembled monolayers (SAMs) in perovskite (PVK) solar cells often presents processing challenges that can hinder their industrial uptake. To address these limitations and enhance the manufacturability of the SAMs/PVK interface, a co-deposition strategy was recently developed, wherein both SAMs and PVK films are formed simultaneously in a single step. As the fundamental principles governing the SAM/PVK co-deposition process remain insufficiently explored, here we selected four commercially available SAMs molecules─MeO-4PACz, Me-4PACz, Me-2PACz, and 2PACz─and we mixed them based on their molecular size, polarity, and hydrophobicity, forming pairs. The co-deposition process of mixed-SAMs with MAPbI3precursor solutions was studied, and corresponding solar cell devices were fabricated. Among the three combinations tested, the MeO-4PACz + Me-4PACz one yields the most promising results, and a power conversion efficiency of approximately 19% was achieved without any additional passivation strategies. Our findings reveal that the co-deposition process of mixed-SAMs is primarily influenced by the interplay between molecular size and polarity. The binding strength of co-deposited mixed SAMs to the In2O3:Sn (ITO) substrate is largely dictated by their solvation behavior in the PVK precursor-DMF:DMSO solvent system. This conclusion is supported by quantum chemistry calculations and further corroborated by surface, structural, and compositional analysis. ... Read more

In organic semiconductor devices, the deposition of organic layers may result in intermixed regions or rough interfaces between layers. To examine how roughness at organic-organic interfaces influences device performance, we conducted mesoscopic device simulations using a three-dimensional kinetic Monte Carlo algorithm. We simulated devices containing interfaces with periodic corrugation of either triangular or rectangular cross section. Our results show how the shape and size of interfacial roughness impacts on both charge and exciton dynamics of unipolar and bipolar devices. We first analyzed bilayer devices where the two layers are energetically offset. We find interfaces with triangular cross section display strong carrier funneling to the tips. This funneling translates to pronounced inhomogeneity in the spatial distribution of charge carriers, excitons, and excitonic losses. The tips act as injection hot spots, increasing the current density by up to two orders of magnitude, depending on the energy offset, compared to a flat-interface device. In contrast, the internal quantum efficiency of bipolar devices is surprisingly unaffected by interfacial morphology. In bipolar three-layer devices, we used this enhancement in current density to improve charge injection toward the central emissive layer. The recombination zone within the emissive layer can also be tuned through the configuration and size of the morphology. ... Read more