cells based on HOIPs have witnessed an unprecedented growth in efficiency in only a few years, faster than any PV technology to date, with power conversion efficiencies greater than 20%. [8] In addition, HOIPs have been incorporated in photodetectors, [9] optically pumped lasers with tunable wavelength, [10] and highefficiency light-emitting diodes. [3] Remarkably, all these devices were manufactured at temperatures below or around 100 °C.The small electron effective mass calculated for HOIPs suggests that the charge carrier mobilities, µ, may be very high in absence of defects and other scattering sites. [11,12] Indeed, mobilities exceeding 100 cm 2 V −1 s −1 were determined in single crystals from space charge limited current (SCLC) and terahertz (THz) spectroscopy measurements. [6,7] The mobilities obtained from field-effect transistors (FETs), however, have been much lower; a maximum value of around 1 cm 2 V −1 s −1 was reported in MAPbX 3 perovskite FETs, [13][14][15] and a maximum of around 2 cm 2 V −1 s −1 in Cs x (M A 0.17 FA 0.83 ) 1−x Pb(Br 0.17 I 0.83 ) 3 triple cation perovskites, [16] despite significant effort dedicated to this topic. [17][18][19][20][21][22] The discrepancy between the measured mobilities with various techniques may arise from the fact that in FETs the interface properties are evaluated, which are prone to defects, whereas the other methods access the bulk properties. On the other hand, recent work suggests that the high mobility values in hybrid perovskites may be an overestimation since the charge transport in these compounds is inhibited due to the existence of a plethora of processes such as polaron formation, [23] scattering from acoustic and optical phonons, [5,11,24] ionic motion, polarization disorder of the organic cations, and dynamic disorder. [14,18,25] A roomtemperature mobility of ≈200 cm 2 V −1 s −1 was predicted in MAPbI 3 in the presence of phonon scattering alone, with no other factors that limit charge carrier transport. [11] It is critical to assess the true intrinsic electrical properties of hybrid perovskites to advance their use in commercial optoelectronic applications. FETs are excellent experimental platforms to access such information with minimal or no approximations necessary. In addition to being the fundamental unit in a wide range of electronic applications, FET devices allow for a basic study of the factors limiting charge transport in perovskites, with a great control over the charge density in the semiconductor layer. Unfortunately, because of the challenges associated with Hybrid organic-inorganic perovskites have recently gained immense attention due to their unique optical and electronic properties and low production cost, which make them promising candidates for a wide range of optoelectronic devices. But unlike most other technologies, the breakthroughs witnessed in hybrid perovskite optoelectronics have outgrown the basic understanding of the fundamental material properties. For example, the effectiveness of charge transport in relation to f...

Charge-carrier transport in thin-film organic semiconductors is strongly related to the molecular structure and the solid-state packing, which in turn are dependent on materials processing and device configurations. We report on the synthesis and characterization of a series of  (trialkylsilyl)­ethynyl-substituted dinaphtho-fused s-indacenes that include three regioisomers: the linear, syn, and anti isomers. Structure–property relationships are established for these antiaromatic compounds by combining X-ray diffraction with field-effect transistor measurements and density functional theory (DFT) evaluations of the electronic band structures and intermolecular electronic couplings. High-performance, solution-processed organic thin-film transistors with charge-carrier mobilities over 7 cm2/(V s) are demonstrated upon optimization of the thin-film morphology. The DFT-derived crystal band structures provide insight into the varied performance metrics observed across the materials, though the fundamental limits of performance are not reached when the film quality is poor. The totality of the results presents the antiaromatic dinaphtho-fused s-indacenes as intriguing building blocks for molecular materials for semiconducting applications.

Fluoride binding by a series of europium and ytterbium complexes of DOTA-tetraamide ligands derived from primary, secondary and tertiary amides has been studied by NMR and luminescence spectroscopies. In all the systems studied, fluoride binding results in a change in the nature of the magnetic anisotropy at the metal centre from an easy axis, to an easy plane anisotropy. This results in reversal of the peaks in the NMR spectra, and in changes to the fine structure of the luminescence spectra. Furthermore, changes to the periphery of the binding cavity are implicated in determining the affinity constant for fluoride. There are clear differences in the entropic contribution to the free energy of activation between systems with benzylic amides and those with methylamides.