TY  - JOUR
A1  - Zeiske, Stefan
A1  - Sandberg, Oskar J.
A1  - Zarrabi, Nasim
A1  - Wolff, Christian Michael
A1  - Raoufi, Meysam
A1  - Peña-Camargo, Francisco
A1  - Gutierrez-Partida, Emilio
A1  - Meredith, Paul
A1  - Stolterfoht, Martin
A1  - Armin, Ardalan
T1  - Static disorder in lead halide perovskites
JF  - The journal of physical chemistry letters
N2  - In crystalline and amorphous semiconductors, the temperature-dependent Urbach energy can be determined from the inverse slope of the logarithm of the absorption spectrum and reflects the static and dynamic energetic disorder. Using recent advances in the sensitivity of photocurrent spectroscopy methods, we elucidate the temperature-dependent Urbach energy in lead halide perovskites containing different numbers of cation components. We find Urbach energies at room temperature to be 13.0 +/- 1.0, 13.2 +/- 1.0, and 13.5 +/- 1.0 meV for single, double, and triple cation perovskite. Static, temperature-independent contributions to the Urbach energy are found to be as low as 5.1 ?+/- 0.5, 4.7 +/- 0.3, and 3.3 +/- 0.9 meV for the same systems. Our results suggest that, at a low temperature, the dominant static disorder in perovskites is derived from zero-point phonon energy rather than structural disorder. This is unusual for solution-processed semiconductors but broadens the potential application of perovskites further to quantum electronics and devices.
KW  - Cations
KW  - External quantum efficiency
KW  - Perovskites
KW  - Solar cells
KW  - Solar energy
Y1  - 2022
U6  - https://doi.org/10.1021/acs.jpclett.2c01652
SN  - 1948-7185
VL  - 13
IS  - 31
SP  - 7280
EP  - 7285
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Mattern, Maximilian
A1  - Pudell, Jan-Etienne
A1  - Laskin, Gennadii
A1  - Reppert, Alexander von
A1  - Bargheer, Matias
T1  - Analysis of the temperature- and fluence-dependent magnetic stress in laser-excited SrRuO3
JF  - Structural dynamics
N2  - We use ultrafast x-ray diffraction to investigate the effect of expansive phononic and contractive magnetic stress driving the picosecond strain response of a metallic perovskite SrRuO3 thin film upon femtosecond laser excitation. We exemplify how the anisotropic bulk equilibrium thermal expansion can be used to predict the response of the thin film to ultrafast deposition of energy. It is key to consider that the laterally homogeneous laser excitation changes the strain response compared to the near-equilibrium thermal expansion because the balanced in-plane stresses suppress the Poisson stress on the picosecond timescale. We find a very large negative Grüneisen constant describing the large contractive stress imposed by a small amount of energy in the spin system. The temperature and fluence dependence of the strain response for a double-pulse excitation scheme demonstrates the saturation of the magnetic stress in the high-fluence regime.
KW  - Thin films
KW  - Thermodynamic properties
KW  - Bragg peak
KW  - Ultrafast X-ray diffraction
KW  - Thermal effects
KW  - Phonons
KW  - Magnetism
KW  - Lattice dynamics
KW  - Lasers
KW  - Perovskites
Y1  - 2020
U6  - https://doi.org/10.1063/4.0000072
SN  - 2329-7778
VL  - 8
IS  - 2
PB  - AIP Publishing LLC
CY  - Melville, NY
ER  -