Robert Gehlhaar
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View article: Revealing Two Operation Modes of Perovskite Light‐Emitting Diodes Through Overshoot Pulses
Revealing Two Operation Modes of Perovskite Light‐Emitting Diodes Through Overshoot Pulses Open
In some applications, perovskite light‐emitting diodes (PeLEDs) shall operate in pulsed mode. The generation of high‐intensity light pulses requires PeLED driving by high‐power electrical pulses, which can lead to deterioration of PeLED pe…
View article: Planar High-Q Evanescent Whispering Gallery Mode Perovskite Lasers
Planar High-Q Evanescent Whispering Gallery Mode Perovskite Lasers Open
Metal halide perovskites (MHPs) are excellent gain media for thin-film laser diodes thanks to their high intrinsic gain and tunable spectral emission properties [1]. Furthermore, perovskite light emitting diodes (PeLEDs) with external quan…
View article: Transient Photoluminescence Reveals the Dynamics of Injected Charge Carriers in Perovskite Light-Emitting Diodes
Transient Photoluminescence Reveals the Dynamics of Injected Charge Carriers in Perovskite Light-Emitting Diodes Open
Understanding the dynamics of injected charge carriers is crucial for the analysis of the perovskite light-emitting diode (PeLED) operation. The behavior of the injected carriers largely dictates the external quantum efficiency (EQE) roll-…
View article: Halide Perovskite Photodiode Integrated CMOS Imager
Halide Perovskite Photodiode Integrated CMOS Imager Open
Thin film photodiodes (TFPD) can supplement complementary metal-oxide-semiconductor (CMOS) image sensor vision by their exotic optoelectronic properties assisted by their monolithic processability. Halide perovskites are known to show outs…
View article: Quasi-bound state in continuum in distributed feedback lasers based on perovskite thin-films
Quasi-bound state in continuum in distributed feedback lasers based on perovskite thin-films Open
Distributed feedback lasers (DFBs) using perovskite gain media can provide many unique properties such as single mode lasing and low pump thresholds. An important characteristic of lasing is the polarization because its control permits to …
View article: Remaining challenges towards high brightness perovskite laser diodes
Remaining challenges towards high brightness perovskite laser diodes Open
We are giving an overview of our work on ultrabright perovskite LEDs with the ultimate goal of injection lasing. Starting from the analysis of perovskite films in standard LED configurations, we can already identify beneficial operation co…
View article: In Situ Annealing Effect on Thermally Co-Evaporated CsPbI<sub>2</sub>Br Thin Films Studied via Spectroscopic Ellipsometry
In Situ Annealing Effect on Thermally Co-Evaporated CsPbI<sub>2</sub>Br Thin Films Studied via Spectroscopic Ellipsometry Open
All-inorganic cesium lead halide perovskites possess excellent thermal stability, a feature that renders them highly favorable for optoelectronic applications with an elevated thermal budget. Employing a coevaporation approach for their de…
View article: Toward Thin‐Film Laser Diodes with Metal Halide Perovskites
Toward Thin‐Film Laser Diodes with Metal Halide Perovskites Open
Metal halide perovskite semiconductors hold a strong promise for enabling thin‐film laser diodes. Perovskites distinguish themselves from other non‐epitaxial media primarily through their ability to maintain performance at high current den…
View article: Estimating the Optically Pumped Threshold Fluence of Thin‐Film Gain Media Using Arbitrary Excitation Beams
Estimating the Optically Pumped Threshold Fluence of Thin‐Film Gain Media Using Arbitrary Excitation Beams Open
Optically pumped threshold fluences are a widely reported metric to benchmark the performance of thin‐film gain media and lasers. Estimating the threshold fluence for nonhomogeneous beams, such as a circular Gaussian excitation, is not tri…
View article: Subwavelength Custom Wavefront Shaping by a Nonlinear Electro-optic Spatial Light Modulator
Subwavelength Custom Wavefront Shaping by a Nonlinear Electro-optic Spatial Light Modulator Open
Holographic displays offer a method to completely reconstruct any desired wavefront and can thus lead to breakthrough innovation in beamforming, sensing, and information encryption. However, full control over a wavefront in the visible req…
View article: COMSOL Fringing Electric Fields in BTO
COMSOL Fringing Electric Fields in BTO Open
A dataset extracted from COMSOL Multiphysics of fringing electric fields inside a Barium Titanate slab waveguide. The fields were used to calculate intricate patterns capable of coupling light out of the waveguide. Both 2D and 3D data is i…
View article: COMSOL Fringing Electric Fields in Barium Titanate
COMSOL Fringing Electric Fields in Barium Titanate Open
A dataset extracted from COMSOL Multiphysics containing fringing electric fields inside a Barium Titanate slab waveguide. These fields were used to calculate intricate patterns capable of coupling light out of the waveguide. Both 2D and 3D…
View article: Wafer-level-integrated vertical-waveguide sub-diffraction-limited color splitters
Wafer-level-integrated vertical-waveguide sub-diffraction-limited color splitters Open
We demonstrate a new technology for splitting colors with sub-micron resolution using standard backend processing on 300 mm wafers. The color splitting is tunable via the geometry and can be designed to correspond to the color sensitivity …
View article: Electric Field-Induced Quenching of MAPbI<sub>3</sub> Photoluminescence in PeLED Architecture
Electric Field-Induced Quenching of MAPbI<sub>3</sub> Photoluminescence in PeLED Architecture Open
Photoluminescence (PL) measurements are a widely used technique for the investigation of perovskite-based materials and devices. Although electric field-induced PL quenching provides additional useful information, this phenomenon is quite …
View article: Scattered Emission Profile Technique for Accurate and Fast Assessment of Optical Gain in Thin Film Lasing Materials
Scattered Emission Profile Technique for Accurate and Fast Assessment of Optical Gain in Thin Film Lasing Materials Open
sponsorship: The authors acknowledge funding from the European Research Council under the European Horizon 2020 Programme/ERC Grant Agreement No. 835133 (ULTRA-LUX) . (European Research Council under the European Horizon 2020 Programme/ERC…
View article: Multimode Lasing in All-Solution-Processed UV-Nanoimprinted Distributed Feedback MAPbI<sub>3</sub> Perovskite Waveguides
Multimode Lasing in All-Solution-Processed UV-Nanoimprinted Distributed Feedback MAPbI<sub>3</sub> Perovskite Waveguides Open
sponsorship: The authors acknowledge funding from the European Research Council under the European Horizon 2020 Programme/ERC grant agreement no. 835133 (ULTRA-LUX) . (European Research Council under the European Horizon 2020 Programme/ERC…
View article: Photonic metamaterial with a subwavelength electrode pattern
Photonic metamaterial with a subwavelength electrode pattern Open
The next generation of tunable photonics requires highly conductive and light inert interconnects that enable fast switching of phase, amplitude, and polarization modulators without reducing their efficiency. As such, metallic electrodes s…
View article: Data File 1.xlsx
Data File 1.xlsx Open
Raw data from ellipsometry measurments.
View article: An embedded interfacial network stabilizes inorganic CsPbI3 perovskite thin films
An embedded interfacial network stabilizes inorganic CsPbI3 perovskite thin films Open
The black perovskite phase of CsPbI 3 is promising for optoelectronic applications; however, it is unstable under ambient conditions, transforming within minutes into an optically inactive yellow phase, a fact that has so far prevented its…
View article: A Thermally Activated Delayed Fluorescence Green OLED with 4500 h Lifetime and 20% External Quantum Efficiency by Optimizing the Emission Zone using a Single‐Emission Spectrum Technique
A Thermally Activated Delayed Fluorescence Green OLED with 4500 h Lifetime and 20% External Quantum Efficiency by Optimizing the Emission Zone using a Single‐Emission Spectrum Technique Open
Device optimization of light‐emitting diodes (LEDs) targets the most efficient conversion of electrically injected charges into emitted light. The emission zone in an LED is where charges recombine and light is emitted from. It is believed…
View article: Intense Electrical Pulsing of Perovskite Light Emitting Diodes under Cryogenic Conditions
Intense Electrical Pulsing of Perovskite Light Emitting Diodes under Cryogenic Conditions Open
As the threshold for stimulated emission is significantly reduced at cryogenic temperatures, cooling of perovskite light emitting diodes (PeLEDs) is considered an essential strategy for reaching injection lasing in perovskite diodes. In th…
View article: Spectroscopic Ellipsometry for Operando Monitoring of (De)Lithiation-Induced Phenomena on LiMn<sub>2</sub>O<sub>4</sub> and LiNi<sub>0.5</sub>Mn<sub>1.5</sub>O<sub>4</sub> Electrodes
Spectroscopic Ellipsometry for Operando Monitoring of (De)Lithiation-Induced Phenomena on LiMn<sub>2</sub>O<sub>4</sub> and LiNi<sub>0.5</sub>Mn<sub>1.5</sub>O<sub>4</sub> Electrodes Open
High voltage cathodes suffer from degradation phenomena that are challenging to be observed and identified during cell operation. Dense and smooth sputtered thin films electrodes with absence of binders and conductive additives allow a dir…
View article: Single emission spectrum measurement enables control of organic LED emission zone giving ultralong device lifetime
Single emission spectrum measurement enables control of organic LED emission zone giving ultralong device lifetime Open
Device optimization of light-emitting diodes targets the most efficient conversion of electrically injected charges into emitted light. Where charges recombine and where light is emitted from is known as the emission zone. Determining its …
View article: All-Evaporated, All-Inorganic CsPbI<sub>3</sub> Perovskite-Based Devices for Broad-Band Photodetector and Solar Cell Applications
All-Evaporated, All-Inorganic CsPbI<sub>3</sub> Perovskite-Based Devices for Broad-Band Photodetector and Solar Cell Applications Open
Following the rapid increase of organic metal halide perovskites toward commercial application in thin-film solar cells, inorganic alternatives attracted great interest with their potential of longer device lifetime due to the stability im…
View article: Operationally Stable Perovskite Light Emitting Diodes with High Radiance
Operationally Stable Perovskite Light Emitting Diodes with High Radiance Open
Although perovskite light emitting diodes (PeLEDs) have shown fast advances in external quantum efficiency (EQE), their operational stability is still low compared to other LED devices. Here, stable PeLEDs are demonstrated with high radian…
View article: Active area dependence of optoelectronic characteristics of perovskite LEDs
Active area dependence of optoelectronic characteristics of perovskite LEDs Open
Active area scaling enables high operational stabilities and extreme brightness
View article: Perovskite Light Emitting Diode Characteristics: The Effects of Electroluminescence Transient and Hysteresis
Perovskite Light Emitting Diode Characteristics: The Effects of Electroluminescence Transient and Hysteresis Open
The reproducibility of results is one of the cornerstones of scientific research. However, in emerging technologies, the reported results often tend to be sensitive to the chosen measurement protocol. This can stem from measurement artifac…
View article: Non-linear electro-optic modelling of a Barium Titanate grating coupler
Non-linear electro-optic modelling of a Barium Titanate grating coupler Open
We provide insight into the driving mechanisms and requirements to create an electro-optic spatial light modulator based on a Barium Titanate waveguide and an optically transparent electrode cladding layer. This cladding is made from alter…
View article: Perovskite modules with 99% geometrical fill factor using point contact interconnections design
Perovskite modules with 99% geometrical fill factor using point contact interconnections design Open
Thin‐film photovoltaic technology, based on hybrid metal halide perovskites, has achieved 25.2% and 16.1% certified power conversion efficiencies for solar cell and solar module devices, respectively. Still, the gap between power conversio…