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2. An embedded interfacial network stabilizes inorganic CsPbI3 perovskite thin films

Author

Steele, Julian A, Braeckevelt, Tom, Prakasam, Vittal, Degutis, Giedrius, Yuan, Haifeng, Jin, Handong, Solano, Eduardo, Puech, Pascal, Basak, Shreya, Pintor-Monroy, Maria Isabel, Van Gorp, Hans, Fleury, Guillaume, Yang, Ruo Xi, Lin, Zhenni, Huang, Haowei, Debroye, Elke, Chernyshov, Dmitry, Chen, Bin, Wei, Mingyang, Hou, Yi, Gehlhaar, Robert, Genoe, Jan, De Feyter, Steven, Rogge, Sven MJ, Walsh, Aron, Sargent, Edward H, Yang, Peidong, Hofkens, Johan, Van Speybroeck, Veronique, and Roeffaers, Maarten BJ

Subjects
Chemical Sciences, Physical Chemistry, Affordable and Clean Energy
Abstract

The black perovskite phase of CsPbI3 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 widespread adoption. Here we use coarse photolithography to embed a PbI2-based interfacial microstructure into otherwise-unstable CsPbI3 perovskite thin films and devices. Films fitted with a tessellating microgrid are rendered resistant to moisture-triggered decay and exhibit enhanced long-term stability of the black phase (beyond 2.5 years in a dry environment), due to increasing the phase transition energy barrier and limiting the spread of potential yellow phase formation to structurally isolated domains of the grid. This stabilizing effect is readily achieved at the device level, where unencapsulated CsPbI3 perovskite photodetectors display ambient-stable operation. These findings provide insights into the nature of phase destabilization in emerging CsPbI3 perovskite devices and demonstrate an effective stabilization procedure which is entirely orthogonal to existing approaches.

Published
2022

7. In Situ Annealing Effect on Thermally Co-Evaporated CsPbI2Br Thin Films Studied via Spectroscopic Ellipsometry

Author

Papadopoulou, Athina, Saha, Rafikul Ali, Pintor-Monroy, Maria Isabel, Song, Wenya, Lieberman, Itai, Solano, Eduardo, Roeffaers, Maarten B. J., Gehlhaar, Robert, and Genoe, Jan

Abstract

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 deposition holds promise for manufacturing at an industrial level, owing to improvements in device scalability and reproducibility. For unlocking the full potential of vacuum-evaporated perovskite thin films, it is crucial to delve deeper into their crystallization process, which, as a solid-state reaction, has been less investigated compared to the crystallization process of, most commonly used, solution-based methods. In this work, we employ spectroscopic ellipsometry, a nondestructive, high speed, and high accuracy characterization method, to study the real time annealing effect on thermally coevaporated CsPbI2Br thin films in a temperature range between 25 and 300 °C. We achieve this by developing a singular dynamic model that can be fitted in real time as a function of temperature, providing insights into how thermal annealing influences the perovskite film’s morphology and optical constants. Based on the latter, we derive the temperature dependence of the thermo-optic coefficient and Urbach energy as well as analyze the interband transition energies via critical point analysis. We demonstrate that the γ- to β-phase transition can be identified through a pronounced shift in the bandgap energy, whereas the β- to α-phase transition can be discerned by a sharp increase in the film’s roughness. We corroborate the obtained fit results with additional in- and ex situ measurements, such as in situ grazing incidence wide-angle X-ray scattering, atomic force microscopy, reflectance/transmittance, and profilometry.

Published
2024
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9. Four‐Dimensional Design Space of High‐Q Second‐Order Distributed Feedback Perovskite Lasers.

Author

Annavarapu, Nirav, Goldberg, Iakov, Hamdad, Sarah, Elkhouly, Karim, Puybaret, Renaud, Sabuncuoglu Tezcan, Deniz, Genoe, Jan, Gehlhaar, Robert, and Heremans, Paul

Subjects
DISTRIBUTED feedback lasers, PEROVSKITE, ACTIVE medium, LASERS, SILICON nitride, SPECTRAL imaging, FOUR-dimensional imaging, LEAD halides
Abstract

Second‐order distributed feedback (DFB) resonators are widely used for thin‐film lasers as they combine low lasing thresholds with ease of manufacturing. Here, the grating design parameters are varied to map the lasing characteristics of lead halide perovskite films deposited on a single substrate that contains hundreds of high‐quality silicon nitride surface gratings. The lowest lasing threshold (≈130 µJ cm−2) is identified through the aid of near‐field and far‐field imaging spectroscopy in a four‐dimensional design space composed of grating period, duty cycle, active layer thickness, and cavity length. Moreover, it is shown that antisymmetric modes support high‐quality lasing (Q up to ≈10800) in the second‐order DFBs. The multi‐dimensional experimental analysis is accompanied by a thorough theoretical study with a semi‐empirical model based on coupled wave equations, which is used to investigate the lasing characteristics beyond the manufacturing range. The results can be applied to a broad range of thin‐film DFB resonators, enabling the design of more complex laser stack configurations including light‐emitting devices for current‐injection lasing. [ABSTRACT FROM AUTHOR]

Published
2024
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16. Image Sensors Using Thin-Film Absorbers

Author

Malinowski, Pawel, primary, Pejovic, Vladimir, additional, Lieberman, Itai, additional, Kim, Joo Hyoung, additional, Siddik, Abu Bakar, additional, Georgitzikis, Epimitheas, additional, Lim, Myung Jin, additional, Moreno Hagelsieb, Luis, additional, Hermans, Yannick, additional, Pintor Monroy, Isabel, additional, Song, Wenya, additional, Basak, Shreya, additional, Gehlhaar, Robert, additional, De Roose, Florian, additional, Siskos, Aris, additional, Papadopoulos, Nikolas, additional, Thijs, Steven, additional, Verschooten, Tom, additional, Chandrasekaran, Naresh, additional, Li, Yunlong, additional, SOUSSAN, PHILIPPE, additional, Genoe, Jan, additional, Heremans, Paul, additional, Lee, Jiwon, additional, and Cheyns, David, additional

Published
2023
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23. Electric Field-Induced Quenching of MAPbI3Photoluminescence in PeLED Architecture

Author

Gegevičius, Rokas, Elkhouly, Karim, Franckevičius, Marius, Chmeliov, Jevgenij, Goldberg, Iakov, Gehlhaar, Robert, Qiu, Weiming, Genoe, Jan, Heremans, Paul, and Gulbinas, Vidmantas

Abstract

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 complex and not yet clearly understood. Here, we address the PL quenching of methylammonium lead iodide (MAPbI3) perovskite in a light-emitting diode (PeLED) architecture. We distinguish two quenching mechanisms: (a) indirect quenching by slow irreversible or partially reversible material changes that occur gradually under the applied light and electric field and (b) direct quenching by the influence of the electric field on the charge carrier densities, their spatial distributions, and radiative recombination rates. Direct quenching, observed under the abrupt application of negative voltage, causes a decrease of the PL intensity. However, the PL intensity then partially recovers within tens of milliseconds as mobile ions screen the internal electric field. The screening time increases to hundreds of seconds at low temperatures, indicating activation energies for ion motion of about 80 meV. On the other hand, ultrafast time-resolved PL measurements revealed two main phases of direct quenching: an instantaneous reduction in the radiative carrier recombination rate, which we attribute to the electron and hole displacement within individual perovskite grains, followed by a second phase lasting hundreds of picoseconds, which is due to the charge carrier extraction and spatial separation of electron and hole “clouds” within the entire perovskite layer thickness.

Published
2023
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24. 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

Author

Mac Ciarnáin, Rossa, primary, Mo, Hin Wai, additional, Nagayoshi, Kaori, additional, Fujimoto, Hiroshi, additional, Harada, Kentaro, additional, Gehlhaar, Robert, additional, Ke, Tung Huei, additional, Heremans, Paul, additional, and Adachi, Chihaya, additional

Published
2022
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27. Interface Control and Characterization of SrTiO3/Si(001)

Author

Wang, Tsang-Hsuan, Gehlhaar, Robert, Conard, Thierry, Genoe, Jan, and Merckling, Clement

Abstract

ispartof: Proc. E-MRS fall ispartof: EMRS fall 2021 location:virtual date:20 Sep - 23 Sep 2021 status: published

Published
2021

32. All-Evaporated, All-Inorganic CsPbI3 Perovskite-Based Devices for Broad-Band Photodetector and Solar Cell Applications

Author

Pintor Monroy, Maria Isabel, primary, Goldberg, Iakov, additional, Elkhouly, Karim, additional, Georgitzikis, Epimitheas, additional, Clinckemalie, Lotte, additional, Croes, Guillaume, additional, Annavarapu, Nirav, additional, Qiu, Weiming, additional, Debroye, Elke, additional, Kuang, Yinghuan, additional, Roeffaers, Maarten B. J., additional, Hofkens, Johan, additional, Gehlhaar, Robert, additional, and Genoe, Jan, additional

Published
2021
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33. Operationally Stable Perovskite Light Emitting Diodes with High Radiance

Author

Elkhouly, Karim, primary, Goldberg, Iakov, additional, Boyen, Hans‐Gerd, additional, Franquet, Alexis, additional, Spampinato, Valentina, additional, Ke, Tung‐Huei, additional, Gehlhaar, Robert, additional, Genoe, Jan, additional, Hofkens, Johan, additional, Heremans, Paul, additional, and Qiu, Weiming, additional

Published
2021
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35. Wafer-scale 2.5D optics in the visible and near infrared for advanced light management

Author

Rottenberg, Xavier, primary, Marcon, Denis, additional, Jansen, Roelof, additional, Figeys, Bruno, additional, Lodewijks, Kristof, additional, De Proft, Anabel, additional, Helin, Philippe, additional, Rochus, Veronique, additional, Rolin, Cedric, additional, Storace, Eleonora, additional, Gehlhaar, Robert, additional, Genoe, Jan, additional, Osman, Haris, additional, Heremans, Paul, additional, Soussan, Philippe, additional, Saseendran, Sandeep, additional, Marinins, Aleksandrs, additional, Vereecke, Bart, additional, Pham, Nga, additional, and Tezcan, Deniz S., additional

Published
2021
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36. IGZO-based Identification Tags Communicating with Everyday Touchscreens

Author

Papadopoulos, Nikolaos, Celiker, Hikmet, Qiu, Weiming, Ameys, Marc, Smout, Steve, Willegems, Myriam, Deroo, Filip, van der Steen, Jan-Laurens, Kronemeijer, Auke Jisk, Dehouwer, Marco, Mityashin, Alexander, Gehlhaar, Robert, Dehaene, Wim, and Myny, Kris

Subjects
Hardware_INTEGRATEDCIRCUITS, Hardware_PERFORMANCEANDRELIABILITY, GeneralLiterature_MISCELLANEOUS
Abstract

In this work, we demonstrate a capacitive coupled data transfer with flexible thin-film electronics using touchscreen as ubiquitous reader interface. The capacitive communication to the touchscreen is proven using a 64-bit metal-oxide thin-film capacitive-coupled identification tag. The tag is powered by a thin film battery or thin-film photovoltaic cell that is converting the light of the screen. The thin-film integrated tag has on-chip monolithic electrodes (0.8cm2), and the integrated circuit employs 409 transistors and dissipates only 140nW of power at 600mV supply voltage. The asynchronous data rate of the chip is up to 35bps, strictly limited by the touchscreen readout electronics.

Published
2020

38. Spectroscopic Ellipsometry for Operando Monitoring of (De) Lithiation-Induced Phenomena on LiMn2O4 and LiNi0.5Mn1.5O4 Electrodes.

Author

Soult, Marta Cazorla, Siller, Valerie, Xinhua Zhu, Gehlhaar, Robert, Wojcik, Pawel J., Morata, Alex, Tarancón, Albert, Vereecken, Philippe M., and Hubin, Annick

Subjects
OXIDE electrodes, ELLIPSOMETRY, TRANSITION metal oxides, ELECTRODES, DIELECTRIC function, TRANSITION metals, HIGH voltages, AQUEOUS electrolytes
Abstract

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 direct study of the active material upon Li insertion and extraction at surface and bulk. Using an operando spectroscopic ellipsometry set-up combined with a customized electrochemical-optical cell (EC-SE), the evolution of the optical absorption and thickness of LiMn2O4 and LiNi0.5Mn1.5O4 thin-film electrodes was monitored upon cycling. Mixed Mn3+/4+ valence in the electrodes and evident layer dissolution associated to Transition Metal (TM) dissolution in the non-aqueous electrolyte at the applied polarization potentials was observed. Our results reaffirm EC-SE as a convenient method to study degradation phenomena in cobalt-free transition metal oxide electrodes. [ABSTRACT FROM AUTHOR]

Published
2022
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42. 78‐4: IGZO‐based Identification Tags Communicating with Everyday Touchscreens

Author

Papadopoulos, Nikolaos, primary, Celiker, Hikmet, additional, Qiu, Weiming, additional, Ameys, Marc, additional, Smout, Steve, additional, Willegems, Myriam, additional, Deroo, Filip, additional, van der Steen, Jan-Laurens, additional, Kronemeijer, Auke Jisk, additional, Dehouwer, Marco, additional, Mityashin, Alexander, additional, Gehlhaar, Robert, additional, Dehaene, Wim, additional, and Myny, Kris, additional

Published
2020
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43. Toward Stable Perovskite Solar Cell Architectures: Robustness Against Temperature Variations of Real-World Conditions

Author

Schwenzer, Jonas A., primary, Rakocevic, Lucija, additional, Abzieher, Tobias, additional, Rueda-Delgado, Diana, additional, Moghadamzadeh, Somayeh, additional, Gharibzadeh, Saba, additional, Hossain, Ihteaz M., additional, Gehlhaar, Robert, additional, Richards, Bryce S., additional, Lemmer, Uli, additional, and Paetzold, Ulrich W., additional

Published
2020
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44. Charge transport and recombination in P3HT:PbS solar cells.

Author

Firdaus, Yuliar, Vandenplas, Erwin, Khetubol, Adis, Cheyns, David, Gehlhaar, Robert, and Van der Auweraer, Mark

Subjects
SOLAR cells, QUANTUM dots, THIN film transistors, ELECTRON recombination, DIRECT energy conversion, CHARGE carriers
Abstract

The charge carrier transport in thin film hybrid solar cells is analyzed and correlated with device performance and the mechanisms responsible for recombination loss. The hybrid bulk heterojunction consisted of a blend of poly(3-hexylthiophene) (P3HT) and small size (2.4 nm) PbS quantum dots (QDs). The charge transport in the P3HT:PbS blends was determined by measuring the space-charge limited current in hole-only and electron-only devices. When the loading of PbS QDs exceeds the percolation threshold, a significant increase of the electron mobility is observed in the blend with PbS QDs. The hole mobility, on the other hand, only slightly decreased upon increasing the loading of PbS QDs. We also showed that the photocurrent is limited by the low shunt resistance rather than by space-charge effects. The significant reduction of the fill factor at high light intensity suggests that under these conditions the non-geminate recombination dominates. However, at open-circuit conditions, the trap-assisted recombination dominates over nongeminate recombination. [ABSTRACT FROM AUTHOR]

Published
2015
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45. Loss Analysis in Perovskite Photovoltaic Modules

Author

Rakocevic, Lucija, primary, Mundt, Laura E., additional, Gehlhaar, Robert, additional, Merckx, Tamara, additional, Aernouts, Tom, additional, Schubert, Martin C., additional, Glunz, Stefan W., additional, and Poortmans, Jef, additional

Published
2019
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46. Reduced Efficiency Roll‐Off and Improved Stability of Mixed 2D/3D Perovskite Light Emitting Diodes by Balancing Charge Injection

Author

Fakharuddin, Azhar, primary, Qiu, Weiming, additional, Croes, Guillaume, additional, Devižis, Andrius, additional, Gegevičius, Rokas, additional, Vakhnin, Alexander, additional, Rolin, Cedric, additional, Genoe, Jan, additional, Gehlhaar, Robert, additional, Kadashchuk, Andrey, additional, Gulbinas, Vidmantas, additional, and Heremans, Paul, additional

Published
2019
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48. Model for the Prediction of the Lifetime and Energy Yield of Methyl Ammonium Lead Iodide Perovskite Solar Cells at Elevated Temperatures

Author

Bastos, João P., primary, Uytterhoeven, Griet, additional, Qiu, Weiming, additional, Paetzold, Ulrich W., additional, Cheyns, David, additional, Surana, Supriya, additional, Rivas, Javier, additional, Jaysankar, Manoj, additional, Song, Wenya, additional, Aernouts, Tom, additional, Poortmans, Jef, additional, and Gehlhaar, Robert, additional

Published
2019
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