An electrical and optical energy gaps separation strategy is put forward for the design of organic wide bandgap semiconductors. This new principle could achieve optimization of wide bandgap (both high singlet and triplet energies) and favorable carrier injection energy levels simultaneously.

Design of novel materials for efficient solar energy conversion is critical to the development of green energy technology. In this work, we present a first-principles study on the design of nanostructures for solar energy harvesting on the basis of the density functional theory. We show that the indirect band structure of bulk silicon nitride is transferred to direct bandgap in nanowire. We fin...

Eq. 1 in this Letter (and also, Eq. 1.133 in ref 2) represents the temperature required for the maximum of Planck’s distribution expressed in units of wavelength to match the bandgap energy. However, the energy at which the maximum occurs depends on whether we consider energy flux per unit frequency range or per unit wavelength range3,4. A more appropriate approximation matches the maximum of P...

Cadmium telluride (CdTe) has been recognized as a promising photovoltaic material for thin-film solar cells because of its near optimum bandgap of ~1.5 eV and high absorption coefficient. The energy gap is near optimum for a single junction solar cell and the high absorption coefficient allows films as thin as 2 μm to absorb more than 98% of the above-bandgap radiation. Cells with efficiencies ...

We studied the optical properties of as-prepared (amorphous) and thermally crystallized (fcc) flash evaporated Ge2Sb2Te5 thin films using variable angle spectroscopic ellipsometry in the photon energy range 0.54 4.13 eV. We employed Tauc-Lorentz model (TL) and CodyLorentz model (CL) for amorphous phase and Tauc-Lorentz model with one additional Gaussian oscillator for fcc phase data analysis. T...

Tuning the bandgap in ferroelectric complex oxides is a possible route for improving the photovoltaic activity of materials. Here, we report the realization of this effect in epitaxial thin films of the ferroelectric complex oxide Bi3.25La0.75Ti3O12 (BLT) suitably doped by Fe and Co. Our study shows that Co (BLCT) doping and combined Fe, Co (BLFCT) doping lead to a reduction of the bandgap by m...

Through introducing a probe layer of bis(4,6-difluorophenylpyridinato-N,C2)picolinatoiridium (FIrpic) between QD emission layer and 4, 4-N, N- dicarbazole-biphenyl (CBP) hole transport layer, we successfully demonstrate that the electroluminescence (EL) mechanism of the inverted quantum dot light-emitting diodes (QD-LEDs) with a ZnO nanoparticle electron injection/transport layer should be dire...

Measurement of InAsSb bandgap energy and InAs/InAsSb band edge positions using spectroscopic ellipsometry and photoluminescence spectroscopy" The structural and optical properties of lattice-matched InAs 0.911 Sb 0.089 bulk layers and strain-balanced InAs/InAs 1Àx Sb x (x $ 0.1–0.4) superlattices grown on (100)-oriented GaSb substrates by molecular beam epitaxy are examined using X-ray diffract...

In this study graphene oxide (GO) was synthesized by using Hummer’s method. Low dimension graphene quantum dot nanoparticles (GQDs) were synthesized using pulse laser irradiation. Fourier Transform-Infrared Spectroscopy (FTIR), Ultraviolet-Visible (UV-Vis) spectroscopy and photoluminescence (PL) analysis were applied to study the GQDs characteristic. Scanning electron microscopy illustrated the...

Accurate optical methods are required to determine the energy bandgap of amorphous semiconductors and elucidate the role of quantum confinement in nanometer-scale, ultra-thin absorbing layers. Here, we provide a critical comparison between well-established methods that are generally employed to determine the optical bandgap of thin-film amorphous semiconductors, starting from normal-incidence r...