A series of In2O3 thin films, ranging from X-ray diffraction amorphous to highly crystalline, were grown on amorphous silica substrates using pulsed laser deposition by varying the film growth temperature. The amorphous-to-crystalline transition and the structure of amorphous In2O3 were investigated by grazing angle X-ray diffraction (GIXRD), Hall transport measurement, high resolution transmission electron microscopy (HRTEM), electron diffraction, extended X-ray absorption fine structure (EXAFS), and ab initio molecular dynamics (MD) liquid-quench simulation. On the basis of excellent agreement between the EXAFS and MD results, a model of the amorphous oxide structure as a network of InOx polyhedra was constructed. Mechanisms for the transport properties observed in the crystalline, amorphous-to-crystalline, and amorphous deposition regions are presented, highlighting a unique structure–property relationship.

The nature of charge transport and local structure are investigated in amorphous indium oxide‐based thin films fabricated by spin‐coating. The In–X–O series where X = Sc, Y, or La is investigated to understand the effects of varying both the X cation ionic radius (0.89–1.17 Å) and the film processing temperature (250–300 °C). Larger cations in particular are found to be very effective amorphosizers and enable the study of high mobility (up to 9.7 cm2 V−1 s−1) amorphous oxide semiconductors without complex processing. Electron mobilities as a function of temperature and gate voltage are measured in thin‐film transistors, while X‐ray absorption spectroscopy and ab initio molecular dynamics simulations are used to probe local atomic structure. It is found that trap‐limited conduction and percolation‐type conduction mechanisms convincingly model transport for low‐ and high‐temperature processed films, respectively. Increased cation size leads to increased broadening of the tail states (10–23 meV) and increased percolation barrier heights (24–55 meV) in the two cases. For the first time in the amorphous In–X–O system, such effects can be explained by local structural changes in the films, including decreased In–O and In–M (M = In, X) coordination numbers, increased bond length disorder, and changes in the MO x polyhedra interconnectivity.

Structural properties of amorphous In-based oxides, In-X-O with X=Zn, Ga, Sn, or Ge, are investigated using ab-initio molecular dynamics liquid-quench simulations. The results reveal that

Organic-inorganic hybrid halide perovskites are emerging as one of the potential materials in the photovoltaic community due to its attractive power conversion efficiency and cost-effective device fabrication. The photovoltaic performance of hybrid halide perovskite is linked to its atomic and electronic structure at the surface. Here we have used electronic structure calculations to determine the structural and electronic properties at the surface of MABX3 (MA = CH3NH3; B = Sn or Pb; X= I, Br, or Cl) perovskites. Next, we compared calculated electronic properties of the surface with the corresponding bulk values. Our results reveal that the structural properties like B-X distances, B-X-B angles, and orientation of MA are different between bulk to perovskite surface. Such changes in structural features at the perovskite surface lead to change in the band gap between surface and bulk perovskite. Both structural features and the band gap at the surface are found to be dependent on the crystal symmetry and chemistry of the perovskite. Further, for all perovskite compositions investigated, no midgap surface electronic states were observed.

The power conversion efficiency of perovskite solar cells can be significantly improved if recombination losses and hysteresis effects, often caused by the presence of structural and chemical defects present at grain boundaries and interfaces, can be minimized during the processing of photoactive layers. As a crucial first step to address this issue, we performed density functional theory calculations to evaluate the electronic structure of the energetically favored (110) perovskite surface in the presence of the widely reported IPb antisite defects. Our calculations indicate that the nature of trap states formed is different for the perovskite surface with exposed methylammonium (MAI) and lead iodide (PbI2) terminating groups. While, in MAI terminated surfaces, IPb antisite defects lead to shallow states close to the valence band, both deep and shallow states are created in the bandgap region in the PbI2 terminated surface. Furthermore, we determined contribution from individual atoms to the trap states and inferred that the trap states originate from the clusters of iodine atoms that are formed near the defect site. The exact nature of the defect state is strongly correlated with the atomic structure of these clusters and can be potentially tuned by controlling the processing conditions of the perovskite film.