TY  - JOUR
A1  - Helland, Vanessa Carolina Figuera
A1  - Gapelyuk, Andrej
A1  - Suhrbier, Alexander
A1  - Riedl, Maik
A1  - Penzel, Thomas
A1  - Kurths, Jürgen
A1  - Wessel, Niels
T1  - Investigation of an automatic sleep stage classification by means of multiscorer hypnogram
N2  - Objectives: Scoring sleep visually based on polysomnography is an important but time-consuming element of sleep medicine. Where-as computer software assists human experts in the assignment of sleep stages to polysomnogram epochs, their performance is usually insufficient. This study evaluates the possibility to fully automatize sleep staging considering the reliability of the sleep stages available from human expert sleep scorers. Methods: We obtain features from EEG, ECG and respiratory signals of polysomnograms from ten healthy subjects. Using the sleep stages provided by three human experts, we evaluate the performance of linear discriminant analysis on the entire polysomnogram and:only on epochs where the three experts agree in their-sleep stage scoring. Results: We show that in polysomnogram intervals, to which all three scorers assign the same sleep stage, our algorithm achieves 90% accuracy. This high rate of agreement with the human experts is accomplished with only a small set of three frequency features from the EEG. We increase-the performance to 93% by including ECG and respiration features. In contrast, on intervals of ambiguous sleep stage, the sleep stage classification obtained from our algorithm, agrees with the human consensus scorer in approximately 61%. Conclusions: These findings suggest that machine classification is highly consistent with human sleep staging and that error in the algorithm's assignments is rather a problem of lack of well-defined criteria for human experts to judge certain polysomnogram epochs than an insufficiency of computational procedures
Y1  - 2010
UR  - http://www.schattauer.de/index.php?id=103&L=1
U6  - https://doi.org/10.3414/Me09-02-0052
SN  - 0026-1270
ER  - 
TY  - JOUR
A1  - Hörmann, Ulrich
A1  - Zeiske, Stefan
A1  - Piersimoni, Fortunato
A1  - Hoffmann, Lukas
A1  - Schlesinger, Raphael
A1  - Koch, Norbert
A1  - Riedl, Thomas
A1  - Andrienko, Denis
A1  - Neher, Dieter
T1  - Stark effect of hybrid charge transfer states at planar ZnO/organic interfaces
JF  - Physical review : B, Condensed matter and materials physics
N2  - We investigate the bias dependence of the hybrid charge transfer state emission at planar heterojunctions between the metal oxide acceptor ZnO and three donor molecules. The electroluminescence peak energy linearly increases with the applied bias, saturating at high fields. Variation of the organic layer thickness and deliberate change of the ZnO conductivity through controlled photodoping allow us to confirm that this bias-induced spectral shift relates to the internal electric field in the organic layer rather than the filling of states at the hybrid interface. We show that existing continuum models overestimate the hole delocalization and propose a simple electrostatic model in which the linear and quadratic Stark effects are explained by the electrostatic interaction of a strongly polarizable molecular cation with its mirror image.
Y1  - 2018
U6  - https://doi.org/10.1103/PhysRevB.98.155312
SN  - 2469-9950
SN  - 2469-9969
VL  - 98
IS  - 15
PB  - American Physical Society
CY  - College Park
ER  - 
TY  - JOUR
A1  - Brinkmann, Kai Oliver
A1  - Becker, Tim
A1  - Zimmermann, Florian
A1  - Kreusel, Cedric
A1  - Gahlmann, Tobias
A1  - Theisen, Manuel
A1  - Haeger, Tobias
A1  - Olthof, Selina
A1  - Tückmantel, Christian
A1  - Günster, M.
A1  - Maschwitz, Timo
A1  - Göbelsmann, Fabian
A1  - Koch, Christine
A1  - Hertel, Dirk
A1  - Caprioglio, Pietro
A1  - Peña-Camargo, Francisco
A1  - Perdigón-Toro, Lorena
A1  - Al-Ashouri, Amran
A1  - Merten, Lena
A1  - Hinderhofer, Alexander
A1  - Gomell, Leonie
A1  - Zhang, Siyuan
A1  - Schreiber, Frank
A1  - Albrecht, Steve
A1  - Meerholz, Klaus
A1  - Neher, Dieter
A1  - Stolterfoht, Martin
A1  - Riedl, Thomas
T1  - Perovskite-organic tandem solar cells with indium oxide interconnect
JF  - Nature
N2  - Multijunction solar cells can overcome the fundamental efficiency limits of single-junction devices. The bandgap tunability of metal halide perovskite solar cells renders them attractive for multijunction architectures(1). Combinations with silicon and copper indium gallium selenide (CIGS), as well as all-perovskite tandem cells, have been reported(2-5). Meanwhile, narrow-gap non-fullerene acceptors have unlocked skyrocketing efficiencies for organic solar cells(6,7). Organic and perovskite semiconductors are an attractive combination, sharing similar processing technologies. Currently, perovskite-organic tandems show subpar efficiencies and are limited by the low open-circuit voltage (V-oc) of wide-gap perovskite cells(8) and losses introduced by the interconnect between the subcells(9,10). Here we demonstrate perovskite-organic tandem cells with an efficiency of 24.0 per cent (certified 23.1 per cent) and a high V-oc of 2.15 volts. Optimized charge extraction layers afford perovskite subcells with an outstanding combination of high V-oc and fill factor. The organic subcells provide a high external quantum efficiency in the near-infrared and, in contrast to paradigmatic concerns about limited photostability of non-fullerene cells(11), show an outstanding operational stability if excitons are predominantly generated on the non-fullerene acceptor, which is the case in our tandems. The subcells are connected by an ultrathin (approximately 1.5 nanometres) metal-like indium oxide layer with unprecedented low optical/electrical losses. This work sets a milestone for perovskite-organic tandems, which outperform the best p-i-n perovskite single junctions(12) and are on a par with perovskite-CIGS and all-perovskite multijunctions(13).
Y1  - 2022
U6  - https://doi.org/10.1038/s41586-022-04455-0
SN  - 0028-0836
SN  - 1476-4687
VL  - 604
IS  - 7905
SP  - 280
EP  - 286
PB  - Nature Research
CY  - Berlin
ER  -