4 research outputs found
Exploring Thermochromic Behavior of Hydrated Hybrid Perovskites in Solar Cells
Highly reproducible and reversible
thermochromic nature of dihydrated
methylammonium lead iodide is found. A wide bandgap variation of the
material (∼2 eV) is detected between room temperature and 60
°C under ambient condition as a result of phase transition caused
by moisture absorption and desorption. In situ X-ray diffraction and
Fourier transform infrared spectroscopy studies are performed to understand
the mechanistic behavior during the phase transition. This thermochromic
property is further explored as absorber material in mesostructured
solar cells. Temperature-dependent reversible power conversion efficiency
greater than 1% under standard test conditions is demonstrated; revealing
its potential applicability in building integrated photovoltaics
Pseudohalide (SCN<sup>–</sup>)‑Doped MAPbI<sub>3</sub> Perovskites: A Few Surprises
Pseudohalide thiocyanate anion (SCN<sup>–</sup>) has been
used as a dopant in a methylammonium lead tri-iodide (MAPbI<sub>3</sub>) framework, aiming for its use as an absorber layer for photovoltaic
applications. The substitution of SCN<sup>–</sup> pseudohalide
anion, as verified using Fourier transform infrared (FT-IR) spectroscopy,
results in a comprehensive effect on the optical properties of the
original material. Photoluminescence measurements at room temperature
reveal a significant enhancement in the emission quantum yield of
MAPbI<sub>3–<i>x</i></sub>(SCN)<sub><i>x</i></sub> as compared to MAPbI<sub>3</sub>, suggestive of suppression
of nonradiative channels. This increased intensity is attributed to
a highly edge specific emission from MAPbI<sub>3–<i>x</i></sub>(SCN)<sub><i>x</i></sub> microcrystals as revealed
by photoluminescence microscopy. Fluoresence lifetime imaging measurements
further established contrasting carrier recombination dynamics for
grain boundaries and the bulk of the doped material. Spatially resolved
emission spectroscopy on individual microcrystals of MAPbI<sub>3–<i>x</i></sub>(SCN)<sub><i>x</i></sub> reveals that the
optical bandgap and density of states at various (local) nanodomains
are also nonuniform. Surprisingly, several (local) emissive regions
within MAPbI<sub>3–<i>x</i></sub>(SCN)<sub><i>x</i></sub> microcrystals are found to be optically unstable
under photoirradiation, and display unambiguous temporal intermittency
in emission (blinking), which is extremely unusual and intriguing.
We find diverse blinking behaviors for the undoped MAPbI<sub>3</sub> crystals as well, which leads us to speculate that blinking may
be a common phenomenon for most hybrid perovskite materials
Pseudohalide (SCN<sup>–</sup>)‑Doped MAPbI<sub>3</sub> Perovskites: A Few Surprises
Pseudohalide thiocyanate anion (SCN<sup>–</sup>) has been
used as a dopant in a methylammonium lead tri-iodide (MAPbI<sub>3</sub>) framework, aiming for its use as an absorber layer for photovoltaic
applications. The substitution of SCN<sup>–</sup> pseudohalide
anion, as verified using Fourier transform infrared (FT-IR) spectroscopy,
results in a comprehensive effect on the optical properties of the
original material. Photoluminescence measurements at room temperature
reveal a significant enhancement in the emission quantum yield of
MAPbI<sub>3–<i>x</i></sub>(SCN)<sub><i>x</i></sub> as compared to MAPbI<sub>3</sub>, suggestive of suppression
of nonradiative channels. This increased intensity is attributed to
a highly edge specific emission from MAPbI<sub>3–<i>x</i></sub>(SCN)<sub><i>x</i></sub> microcrystals as revealed
by photoluminescence microscopy. Fluoresence lifetime imaging measurements
further established contrasting carrier recombination dynamics for
grain boundaries and the bulk of the doped material. Spatially resolved
emission spectroscopy on individual microcrystals of MAPbI<sub>3–<i>x</i></sub>(SCN)<sub><i>x</i></sub> reveals that the
optical bandgap and density of states at various (local) nanodomains
are also nonuniform. Surprisingly, several (local) emissive regions
within MAPbI<sub>3–<i>x</i></sub>(SCN)<sub><i>x</i></sub> microcrystals are found to be optically unstable
under photoirradiation, and display unambiguous temporal intermittency
in emission (blinking), which is extremely unusual and intriguing.
We find diverse blinking behaviors for the undoped MAPbI<sub>3</sub> crystals as well, which leads us to speculate that blinking may
be a common phenomenon for most hybrid perovskite materials
Pseudohalide (SCN<sup>–</sup>)‑Doped MAPbI<sub>3</sub> Perovskites: A Few Surprises
Pseudohalide thiocyanate anion (SCN<sup>–</sup>) has been
used as a dopant in a methylammonium lead tri-iodide (MAPbI<sub>3</sub>) framework, aiming for its use as an absorber layer for photovoltaic
applications. The substitution of SCN<sup>–</sup> pseudohalide
anion, as verified using Fourier transform infrared (FT-IR) spectroscopy,
results in a comprehensive effect on the optical properties of the
original material. Photoluminescence measurements at room temperature
reveal a significant enhancement in the emission quantum yield of
MAPbI<sub>3–<i>x</i></sub>(SCN)<sub><i>x</i></sub> as compared to MAPbI<sub>3</sub>, suggestive of suppression
of nonradiative channels. This increased intensity is attributed to
a highly edge specific emission from MAPbI<sub>3–<i>x</i></sub>(SCN)<sub><i>x</i></sub> microcrystals as revealed
by photoluminescence microscopy. Fluoresence lifetime imaging measurements
further established contrasting carrier recombination dynamics for
grain boundaries and the bulk of the doped material. Spatially resolved
emission spectroscopy on individual microcrystals of MAPbI<sub>3–<i>x</i></sub>(SCN)<sub><i>x</i></sub> reveals that the
optical bandgap and density of states at various (local) nanodomains
are also nonuniform. Surprisingly, several (local) emissive regions
within MAPbI<sub>3–<i>x</i></sub>(SCN)<sub><i>x</i></sub> microcrystals are found to be optically unstable
under photoirradiation, and display unambiguous temporal intermittency
in emission (blinking), which is extremely unusual and intriguing.
We find diverse blinking behaviors for the undoped MAPbI<sub>3</sub> crystals as well, which leads us to speculate that blinking may
be a common phenomenon for most hybrid perovskite materials