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Transition metal doped ${\mathrm{In}}_{2}{\mathrm{O}}_{3}$ with high mobility can be used as a transparent conductor with enhanced transparency spectral window. In this work, we carried out a comprehensive study on the electrical and optical properties of ${\mathrm{In}}_{2}{\mathrm{O}}_{3}$ doped with several transition metal (TM) species (${\mathrm{In}}_{2}{\mathrm{O}}_{3}:\mathrm{TM}$) including W, Zr, Mo, and Ti. Detailed optical properties obtained by spectroscopic ellipsometry (SE) are correlated with electrical properties obtained by Hall effect measurements. We find that the mobility of ${\mathrm{In}}_{2}{\mathrm{O}}_{3}:\mathrm{TM}$ thin films lies in the range of $50\text{--}75\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{2}\phantom{\rule{0.16em}{0ex}}{\mathrm{V}}^{\text{\ensuremath{-}}1}\phantom{\rule{0.16em}{0ex}}{\mathrm{s}}^{\text{\ensuremath{-}}1}$, much higher than the typical mobility of $30\text{--}40\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{2}\phantom{\rule{0.16em}{0ex}}{\mathrm{V}}^{\text{\ensuremath{-}}1}\phantom{\rule{0.16em}{0ex}}{\mathrm{s}}^{\text{\ensuremath{-}}1}$ for conventional ITO. The complex dielectric functions of the thin films reveal remarkable carrier density dependent changes in the optical properties. SE analyses show that the electron effective mass of ${\mathrm{In}}_{2}{\mathrm{O}}_{3}:\mathrm{TM}$ at the bottom of the conduction band ${m}_{o}^{*}$ ($0.11\text{--}0.14{m}_{o}$) is much smaller than the reported ${m}_{o}^{*}\ensuremath{\sim}0.18\ensuremath{-}0.30{m}_{o}$ for ITO, which directly results in their higher mobility. This low ${m}_{o}^{*}$ is consistent with recent theoretical studies which proposed that $4d$ donor states of the TMs are resonance in the CB. For films with comparably low resistivity of $1\text{--}2\ifmmode\times\else\texttimes\fi{}{10}^{\text{\ensuremath{-}}4}\phantom{\rule{0.16em}{0ex}}\mathrm{\ensuremath{\Omega}}\phantom{\rule{0.16em}{0ex}}\mathrm{cm}$, we find that ${\mathrm{In}}_{2}{\mathrm{O}}_{3}:\mathrm{TM}$ films have \ensuremath{\sim}4--10 times lower absorption coefficient at $\ensuremath{\lambda}=1300\phantom{\rule{0.16em}{0ex}}\mathrm{nm}$ due to free carrier absorption and have their plasma reflection edge extended to \ensuremath{\sim}1.7 \ensuremath{\mu}m compared to \ensuremath{\sim}1.2--1.4 \ensuremath{\mu}m for ITO. Hence, using TM doping we have achieved transparent conductors with conductivity comparable to ITO but with transmission extended to g1600 nm. These materials will be potentially important as transparent conductors for optoelectronic devices utilizing NIR photons.

Bismuth chalcogenides are promising materials for thermoelectric (TE) application due to their high power factor (product of the square of the Seebeck coefficient and electrical conductivity). However, their high thermal conductivity is an issue of concern. Single doping has proven to be useful in improving TE performance in recent years. Here, it is shown that dual isovalent doping shows the synergistic effect of thermal conductivity reduction and electron density control. The insertion of large atoms in the layered Bi2Te3 structure distorts the crystal lattice and contributes significantly to phonon scattering. The ultralow thermal conductivity (KT = 0.35 W m−1 K−1 at 473 K) compensates for the low power factor and thus enhances TE performance. The density functional theory electronic structure calculation results reveal deep defects states in the valence band, which influences the electronic transport properties of the system. Therefore, the dual dopants (indium and antimony) show a coupled effect of improvement in the density of state near the Fermi level and reduction in the conduction band minimum, thus enhancing electron density. Numerically, it is demonstrated that the dual doping favors acoustic phonon scattering and thus drastically reduces the thermal conductivity.

Significant enhancement of the light emission in Ruddlesden–Popper organic–inorganic halide perovskites is obtained by antisolvent induced spontaneous formation of nanocrystals in an amorphous matrix. This morphology change results in the passivation of defects and significant enhancement of light emission and 16 times higher photoluminescence quantum yield (PLQY), and it is applicable to different spacer cations. The use of trioctylphosphine oxide results in further defect passivation leading to an increase in PLQY (≈2.3 times), the suppression of lower energy emission in low temperature photoluminescence spectra, the dominance of radiative recombination, and the disappearance of thermal quenching of the luminescence. The proposed method offers a reproducible, controllable, and antisolvent‐ insensitive alternative to energy landscape engineering to utilize energy funneling phenomenon to achieve bright emission. Instead of facilitating fast energy transfer from lower to higher number of perovskite sheets to prevent nonradiative losses, it is demonstrated that defects can be effectively passivated via morphology control and the use of a passivating agent, so that bright emission can be obtained from single phase nanocrystals embedded in amorphous matrix, resulting in light emitting diodes with a maximum external quantum efficiency of 2.25%.