2 research outputs found
First-Principles Screening and Design of Novel Triphenylamine-Based D−π–A Organic Dyes for Highly Efficient Dye-Sensitized Solar Cells
We screen a series
of π-conjugated bridge groups and design
a range of metal-free organic donor−π–acceptor
(D−π–A) <b>SPL101</b>–<b>SPL108</b> dyes based on the experimentally synthesized <b>C217</b> dye
for highly efficient dye-sensitized solar cells (DSSC) using density
functional theory (DFT) and time-dependent DFT (TDDFT), and further
calculate their physical and electronic properties, including geometrical
structures, electronic cloud distribution, molecular orbital energy
levels, absorption spectra, light harvesting efficiency (LHE), driving
force of injection (Δ<i>G</i><sub>inj</sub>) and regeneration
(Δ<i>G</i><sub>reg</sub>), and electron dipole moment
(μ<sub>normal</sub>). Results reveal that the π-conjugated
bridge groups in <b>SPL103</b> and <b>SPL104</b> are promising
functional groups for D−π–A organic dyes. In particular,<b> SPL106 </b>and<b> SPL108</b> have not only smaller energy
gaps, higher molar extinction coefficients, and 128 and 143 nm redshifts,
but also a broader absorption spectrum covering the entire visible
range up to the near-IR region of 1200 nm compared to <b>C217</b> dye
Effect of Bromine Substitution on the Ion Migration and Optical Absorption in MAPbI<sub>3</sub> Perovskite Solar Cells: The First-Principles Study
In the past few years,
the remarkable energy conversion efficiency of lead-halide-based perovskite
solar cells (PSCs) has drawn extraordinary attention. However, some
exposed problems in PSCs such as the low chemical stability and so
forth are tough to eliminate. A fundamental understanding of ionic
transport at the nanoscale is essential for developing high-performance
PSCs based on the anomalous hysteresis current–voltage (<i>I</i>–<i>V</i>) curves and the poor stability.
Our work is to understand the ionic transport mechanism by introducing
suitable halogen substitution with insignificant impact on light absorption
to hinder ion diffusion and thereby to seek a method to improve the
stability. Herein, we used first-principles density functional theory
(DFT) to calculate the band gaps and the optical absorption coefficients,
and the interstitial and the vacancy defect diffusion barriers of
halide in the orthogonal phase MAPbX<sub>3</sub> (MA = CH<sub>3</sub>NH<sub>3</sub>, X = I, Br, I<sub>0.5</sub>Br<sub>0.5</sub>) perovskite,
respectively. The research results show that a half bromine substitution
not only prevents ion migration in perovskite, but also maintains
a favorable light absorption capacity. It may be helpful to maintain
the PSC’s property of light absorption with a similar atomic
substitution. Furthermore, smaller atomic substitution for the halogen
atoms may be essential for increasing the diffusion barrier