Methylammonium lead halide perovskite-based solar cells have demonstrated efficiencies as high as 24.2 %, highlighting their potential as inexpensive and solution-processable alternatives to silicon solar cell technologies.P oor stability towards moisture,u ltraviolet irradiation, heat, and ab ias voltage of the perovskite layer and its various device interfaces limits the commercial feasibility of this material for outdoor applications.Herein, we investigate the role of hydrogen bonding interactions induced when metal halide perovskite crystals are crosslinked with alkyl or p-conjugated boronic acid small molecules (-B(OH) 2 ). The crosslinked perovskite crystals are investigated under continuous light irradiation and moisture exposure.These studies demonstrate that the origin of the interaction between the alkylorp-conjugated crosslinking molecules is due to hydrogen bonding between the -B(OH) 2 terminal group of the crosslinker and the Io ft he [PbI 6 ] 4À octahedra of the perovskite layer.A lso,t his interaction influences the stability of the perovskite layer towards moisture and ultraviolet light irradiation. Morphology and structural analyses,aswell as IR studies as afunction of aging under both dark and light conditions showthat p-conjugated boronic acid molecules are more effective crosslinkers of the perovskite crystals than their alkylc ounterparts thus imparting better stability towards light and moisture degradation.

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In this work, we report on the growth of highmobility β-Ga2O3 homoepitaxial thin films grown at a temperature much lower than the conventional growth temperature window for metalorganic vapor phase epitaxy. Low-temperature β-Ga2O3 thin films grown at 600 • C on Fe-doped (010) bulk substrates exhibits remarkable crystalline quality which is evident from the measured room temperature Hall mobility of 186 cm 2 /Vs for the unintentionally doped films. N-type doping is achieved by using Si as a dopant and a controllable doping in the range of 2×10 16 -2×10 19 cm −3 is studied. Si incorporation and activation is studied by comparing silicon concentration from secondary ion mass spectroscopy (SIMS) and electron concentration from temperature-dependent Hall measurements. The films exhibit high purity (low C and H concentrations) with very low concentration of compensating acceptors (2×10 15 cm −3 ) even at this growth temperature. Additionally, abrupt doping profile with forward decay of ∼ 5nm/dec (10 times improvement compared to what is observed for thin films grown at 810 • C) is demonstrated by growing at a lower temperature.

Two‐dimensional coordination polymers (2DCPs) have been predicted to exhibit exotic properties such as superconductivity, topological insulating behavior, catalytic activity, and superior ion transport for energy applications; experimentally, these materials have fallen short of their expectation due to the lack of synthesis protocols that yield continuous, large crystallite domains, and highly ordered thin films with controllable physical and chemical properties. Herein, the fabrication of large‐area, highly ordered 2DCP thin films with large crystallite domains using chemical vapor deposition (CVD) approaches is described. It is demonstrated that defects and the packing motifs of 2DCP thin films may be controlled by adjusting the vapor–vapor and vapor–solid interactions of the metal and organic linker precursors during the CVD fabrication process. Such control allows for the fabrication of defects‐controlled 2DCP thin films that show either semiconducting or metallic behavior. The findings provide the first demonstration of tuning the electrical properties of sub 100 nm‐thick continuous 2DCP thin films by controlling their electronic landscape through defect engineering. As such, it is determined that large‐area, highly ordered 2DCP thin films may undergo a semiconducting to metallic transition that is correlated to changes in morphology, crystalline domain sizes, crystallite orientation, defect interactions, and electronic structure.

We determined how morphology, electronic and interfacial interactions affect perovskite PVs under voltage bias stress. Our findings provide insights into the discrepancies in the solar cell efficiencies observed across many different research groups.

Large size cation (PA) was introduced into the grain boundary and film surface of the 3D perovskite to improve the solar cell efficiency and moisture stability.

Perovskites based on methylammonium lead halides, CH 3 NH 3 PbX 3 (X = Cl, Br, I), have emerged as one of the most promising materials in solar cell technology. Although the photovoltaics field has witnessed significant progress in the power conversion efficiency (PCE) of perovskite solar cells, unveiling the contribution of the various factors (i.e., energy level alignment, trap states, electron (hole) mobility, interface interactions, and morphology) affecting the observed PCEs is extremely crucial to achieve reproducible and stable devices. This work aims to understand charge transport and recombination within conventional perovskite solar cells due to modifications of the morphology, optoelectronic properties, and energy levels of the titania electron transport layer. Here, we utilize two different processing methods (i.e., solution and sputtering depositions) to yield three morphologically different titania electron transport layers (i.e., planar bulk TiO 2 , mesoporous TiO x , and sputtered TiO 2 ). We find that the most important factors affecting the PCEs in perovskite solar cells are related to trap-assisted recombination and energy level alignment due to variations in the electron transport layer/perovskite interface. Similarly, we observe that morphologies of both the electron transport layer and the perovskite active layer play a minor role on the observed PCEs.

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