TY  - JOUR
A1  - Tvingstedt, Kristofer
A1  - Malinkiewicz, Olga
A1  - Baumann, Andreas
A1  - Deibel, Carsten
A1  - Snaith, Henry J.
A1  - Dyakonov, Vladimir
A1  - Bolink, Henk J.
T1  - Radiative efficiency of lead iodide based perovskite solar cells
JF  - Scientific Reports
N2  - The maximum efficiency of any solar cell can be evaluated in terms of its corresponding ability to emit light. We herein determine the important figure of merit of radiative efficiency for Methylammonium Lead Iodide perovskite solar cells and, to put in context, relate it to an organic photovoltaic (OPV) model device. We evaluate the reciprocity relation between electroluminescence and photovoltaic quantum efficiency and conclude that the emission from the perovskite devices is dominated by a sharp band-to-band transition that has a radiative efficiency much higher than that of an average OPV device. As a consequence, the perovskite have the benefit of retaining an open circuit voltage ~0.14 V closer to its radiative limit than the OPV cell. Additionally, and in contrast to OPVs, we show that the photoluminescence of the perovskite solar cell is substantially quenched under short circuit conditions in accordance with how an ideal photovoltaic cell should operate.
KW  - solar cells
KW  - optical spectroscopy
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-119360
VL  - 4
ER  - 
TY  - JOUR
A1  - Astakhov, Georgy V.
A1  - Kraus, Hannes
A1  - Soltamov, V. A.
A1  - Fuchs, Franziska
A1  - Simin, Dimitrij
A1  - Sperlich, Andreas
A1  - Baranov, P. G.
A1  - Dyakonov, Vladimir
T1  - Magnetic field and temperature sensing with atomic-scale spin defects in silicon carbide
N2  - Quantum systems can provide outstanding performance in various sensing applications, ranging from bioscience to nanotechnology. Atomic-scale defects in silicon carbide are very attractive in this respect because of the technological advantages of this material and favorable optical and radio frequency spectral ranges to control these defects. We identified several, separately addressable spin-3/2 centers in the same silicon carbide crystal, which are immune to nonaxial strain fluctuations. Some of them are characterized by nearly temperature independent axial crystal fields, making these centers very attractive for vector magnetometry. Contrarily, the zero-field splitting of another center exhibits a giant thermal shift of −1.1 MHz/K at room temperature, which can be used for thermometry applications. We also discuss a synchronized composite clock exploiting spin centers with different thermal response.
KW  - condensed-matter physics
KW  - quantum physics
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-113025
ER  -