A5081384208- Perovskite Materials and Applications
- Conducting polymers and applications
- Chalcogenide Semiconductor Thin Films
- Quantum Dots Synthesis And Properties
- Organic Electronics and Photovoltaics
- Solid-state spectroscopy and crystallography
- Organic Light-Emitting Diodes Research
- Semiconductor Quantum Structures and Devices
- 2D Materials and Applications
- Thin-Film Transistor Technologies
- Electrochemical Analysis and Applications
- Gas Sensing Nanomaterials and Sensors
- Electronic and Structural Properties of Oxides
- Ion-surface interactions and analysis
- ZnO doping and properties
- Advanced Photocatalysis Techniques
University of Oxford
2021-2025
University of Potsdam
2017-2023
Helmholtz-Zentrum Berlin für Materialien und Energie
2017-2021
State University of New York at Potsdam
2020
HES-SO Valais-Wallis
2020
École Polytechnique Fédérale de Lausanne
2020
Fraunhofer Center for Silicon Photovoltaics
2017
Tandem solar cells that pair silicon with a metal halide perovskite are promising option for surpassing the single-cell efficiency limit. We report monolithic perovskite/silicon tandem certified power conversion of 29.15%. The absorber, bandgap 1.68 electron volts, remained phase-stable under illumination through combination fast hole extraction and minimized nonradiative recombination at hole-selective interface. These features were made possible by self-assembled, methyl-substituted...
Charge transport layers (CTLs) are key components of diffusion controlled perovskite solar cells, however, they can induce additional non-radiative recombination pathways which limit the open circuit voltage (V_OC) cell. In order to realize full thermodynamic potential absorber, both electron and hole layer (ETL/HTL) need be as selective possible. By measuring quasi-Fermi level splitting (QFLS) perovskite/CTL heterojunctions, we quantify interfacial current for a wide range commonly used...
Abstract Today's perovskite solar cells (PSCs) are limited mainly by their open‐circuit voltage ( V OC ) due to nonradiative recombination. Therefore, a comprehensive understanding of the relevant recombination pathways is needed. Here, intensity‐dependent measurements quasi‐Fermi level splitting (QFLS) and on very same devices, including pin‐type PSCs with efficiencies above 20%, performed. It found that QFLS in lies significantly below its radiative limit for all intensities but also...
High fill factor, large area perovskite solar cells are realized with undoped organic transport layers by optimizing the charge carrier transit through PTAA.
Abstract The measurement of the ideality factor ( n id ) is a popular tool to infer dominant recombination type in perovskite solar cells (PSC). However, true meaning its values often misinterpreted complex multilayered devices such as PSC. In this work, effects bulk and interface on are investigated experimentally theoretically. By coupling intensity‐dependent quasi‐Fermi level splitting measurements with drift diffusion simulations complete partial cell stacks, it shown that interfacial...
Abstract Perovskite photovoltaic (PV) cells have demonstrated power conversion efficiencies (PCE) that are close to those of monocrystalline silicon cells; however, in contrast PV, perovskites not limited by Auger recombination under 1‐sun illumination. Nevertheless, compared GaAs and perovskite significantly lower fill factors due a combination resistive non‐radiative losses. This necessitates deeper understanding the underlying loss mechanisms particular ideality factor cell. By measuring...
Perovskites offer exciting opportunities to realize efficient multijunction photovoltaic devices. This requires high-VOC and often Br-rich perovskites, which currently suffer from halide segregation. Here, we study triple-cation perovskite cells over a wide bandgap range (∼1.5–1.9 eV). While all wide-gap (≥1.69 eV) experience rapid phase segregation under illumination, the electroluminescence spectra are less affected by this process. The measurements reveal low radiative efficiency of mixed...
We identify the limiting factors of wide bandgap metal halide perovskite solar cells. To overcome these losses, we developed an efficient optimisation strategy and outline necessary steps for continued development perovskites.
In this work, we couple theoretical and experimental approaches to understand reduce the losses of wide bandgap Br-rich perovskite pin devices at open-circuit voltage (VOC) short-circuit current (JSC) conditions. A mismatch between internal quasi-Fermi level splitting (QFLS) external VOC is detrimental for these devices. We demonstrate that modifying top-surface with guanidinium-Br imidazolium-Br forms a low-dimensional phase n-interface, suppressing QFLS-VOC mismatch, boosting VOC....
Metal halide perovskite based tandem solar cells are promising to achieve power conversion efficiency beyond the theoretical limit of their single-junction counterparts. However, overcoming significant open-circuit voltage deficit present in wide-bandgap remains a major hurdle for realizing efficient and stable cells. Here, holistic approach challenges 1.8 eV is reported by engineering crystallization pathway means chloride additives. In conjunction with employing self-assembled monolayer as...
Abstract The presence of mobile ions in metal halide perovskites has been shown to adversely affect the intrinsic stability perovskite solar cells (PSCs). However, actual contribution total degradation loss compared with other factors such as trap-assisted recombination remains poorly understood. Here we reveal that ion-induced internal field screening is dominant factor PSCs under operational conditions. increased leads a decrease steady-state efficiency, often owing large reduction current...
Perovskite solar cells are among the most exciting photovoltaic systems as they combine low recombination losses, ease of fabrication, and high spectral tunability. The Achilles heel this technology is device stability due to ionic nature perovskite crystal, rendering it highly hygroscopic, extensive diffusion ions especially at increased temperatures. Herein, we demonstrate application a simple solution-processed perfluorinated self-assembled monolayer (p-SAM) that not only enhances cell...
Optimizing the photoluminescence (PL) yield of a solar cell has long been recognized as key principle to maximize power conversion efficiency. While PL measurements are routinely applied perovskite films and cells under open-circuit conditions (VOC), it remains unclear how emission depends on voltage. Here, we performed PL(V) with different hole transport layer thicknesses doping concentrations, resulting in remarkably fill factors (FFs). The results reveal that mirrors current–voltage (JV)...
Monolithic perovskite silicon tandem solar cells can overcome the theoretical efficiency limit of cells. This requires an optimum bandgap, high quantum efficiency, and stability perovskite. Herein, a heterojunction bottom cell is combined with top cell, bandgap 1.68 eV in planar p–i–n configuration. A methylammonium‐free FA 0.75 Cs 0.25 Pb(I 0.8 Br 0.2 ) 3 content investigated for improved stability. 10% molarity increase to 1.1 m precursor solution results ≈75 nm thicker absorber layers 0.7...
Abstract Efficient mixed metal lead‐tin halide perovskites are essential for the development of all‐perovskite tandem solar cells, however they currently limited by significant short‐circuit current losses despite their near optimal bandgap (≈1.25 eV). Herein, origin these is investigated, using a combination voltage dependent photoluminescence (PL) timeseries and various charge extraction measurements. It demonstrated that Pb/Sn‐perovskite devices suffer from reduction in efficiency within...
In this work, we demonstrate how the use of a poly(ionic liquid) interlayer in combination with perovskite solar cells provides bi-functionality surface allowing to concomitantly reduce energy losses, enhance charge extraction and improve device stability all at once.
Perovskite semiconductors have demonstrated outstanding external luminescence quantum yields, enabling high power conversion efficiencies (PCEs). However, the precise conditions to advance an efficiency regime above monocrystalline silicon cells are not well understood. Herein, a simulation model that describes efficient p–i–n‐type perovskite solar and range of different experiments is established. Then, important device material parameters studied it found 30% can be unlocked by optimizing...
Recent advancements in perovskite solar cell performance were achieved by stabilizing the α-phase of FAPbI3 nip-type architectures. However, these could not be directly translated to pin-type devices. Here, we fabricated a high-quality double cation (MA0.07FA0.93PbI3) with low bandgap energy (1.54 eV) using two-step approach on standard polymer (PTAA). The films exhibit large grains (∼1 μm), high external photoluminescence quantum yields 20%, and outstanding Shockley–Read–Hall carrier...
Abstract Successful manipulation of halide perovskite surfaces is typically achieved via the interactions between modulators and perovskites. Herein, it demonstrated that a strong‐interaction surface modulator beneficial to reduce interfacial recombination losses in inverted (p‐i‐n) solar cells (IPSCs). Two organic ammonium salts are investigated, consisting 4‐hydroxyphenethylammonium iodide 2‐thiopheneethylammonium (2‐TEAI). Without thermal annealing, these two can recover photoluminescence...
Although significant progress has been made in the development of green, red, and near-infrared perovskite light-emitting diodes (PeLEDs), blue PeLEDs exhibit inferior performance, owing to various defects poor carrier injection solution-processed films. Thus, this study incorporates dual-passivation additive diphenylphosphinamide (DPPA) into films, through density functional theory calculations experimental characterizations, DPPA proven be an effective passivator. Its phosphine oxide group...