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52
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Introduction
Research interests are centered on the development and application of self-driven Automated Materials and Device Acceleration Platforms (AMADAPs), integrated with machine learning algorithms, specifically for the research of semiconductor materials such as perovskite photovoltaic materials.
Current institution
Additional affiliations
Helmholtz-Institute Erlangen-Nürnberg (HI ERN)
Position
- Research Scientist
Description
- The research department "High-throughput processes in photovoltaics" aims to develop materials, processes and technologies that enable a sustainable and significant cost reduction in photovoltaic technology, from small, off-grid energy generation to large-scale energy production and from the watt to the terawatt scale. The research combines services from automated materials research, digitalization, simulation and big data methods with the specialist knowledge of photovoltaic technology.
Publications
Publications (52)
Sn‐Pb perovskites, a most promising low bandgap semiconductor for multi‐junction solar cells, are often limited in stability due to the susceptibility of Sn2+ to oxidation1,2. Inspired by the antioxidative properties of polyphenolic compounds3,4, we introduce the reductive phenol group and strong electronegative fluorine into an organic conjugated...
Sn─Pb perovskites, a most promising low bandgap semiconductor for multi‐junction solar cells, are often limited by instability due to the susceptibility of Sn²⁺ to oxidation. Inspired by the antioxidative properties of polyphenolic compounds, we introduce the reductive phenol group and strong electronegative fluorine into an organic conjugated stru...
Since its emergence in 2009, perovskite photovoltaic technology has achieved remarkable progress, with efficiencies soaring from 3.8% to over 26%. Despite these advancements, challenges such as long‐term material and device stability remain. Addressing these challenges requires reproducible, user‐independent laboratory processes and intelligent exp...
Traditional optimization methods often face challenges in exploring complex process parameter spaces, which typically result in suboptimal local maxima. Here an autonomous framework driven by a machine learning (ML)‐guided automated platform is introduced to optimize the fabrication conditions of additive‐ and passivation‐free perovskite solar cell...
Perovskite-organic tandem solar cells (P-O-TSCs) hold substantial potential to surpass the theoretical efficiency limits of single-junction solar cells. However, their performance is hampered by non-ideal interconnection layers (ICLs). Especially in n-i-p configurations, the incorporation of metal nanoparticles negatively introduces serious parasit...
The inverse design of tailored organic molecules for specific optoelectronic devices of high complexity holds an enormous potential but has not yet been realized. Current models rely on large data sets that generally do not exist for specialized research fields. We demonstrate a closed-loop workflow that combines high-throughput synthesis of organi...
The development of new solar materials for emerging perovskite photovoltaics poses intricate multi-objective optimization challenges in a large high-dimensional composition and parameter space, with in some cases, millions of potential candidates to be explored. Solving it necessitates reproducible, user-independent laboratory work and intelligent...
High‐energy‐density anode materials are crucial for achieving high performance alkali metal‐ion batteries (AMIBs). In situ transmission electron microscopy (TEM) enables real‐time observation of microstructural changes in electrode materials and interfaces during charging/discharging, crucial for designing high‐performance anodes. This paper highli...
Perovskite-based tandem solar cells stand at the forefront of photovoltaic innovation due to their exceptional performance and cost-effective fabrication. This study focuses on minimizing energy losses within a 1.80 eV perovskite sub-cell. We demonstrate that the surface treatment of perovskite with binary guanidinium bromide and 4-fluorophenylammo...
The inverse design of tailored organic molecules for specific optoelectronic devices of high complexity holds an enormous potential, but has not yet been realized1,2. The complexity and literally infinite diversity of conjugated molecular structures present both, an unprecedented opportunity for technological breakthroughs as well as an unseen opti...
Achieving high-performance perovskite photovoltaics, especially in ambient air, is critically dependent on the precise optimization of process parameters. However, traditional manual methods often struggle to effectively control the key variables. This inherent challenge requires a paradigm shift toward automated platforms capable of precise and re...
Closed-loop recycling is crucial in the rapidly expanding era of photovoltaic deployment. Yet, the recycling of commercial silicon photovoltaic modules presents challenges due to laborious component separation. In contrast, layers in solution-processed solar cells can be separated with relative ease through selective dissolution. In this study, we...
Reliable fabrication of large‐area perovskite films with antisolvent‐free printing techniques requires high‐volatility solvents, such as 2‐methoxyethanol (2ME), to formulate precursor inks. However, the fabrication of high‐quality cesium–formamidinium (Cs–FA) perovskites has been hampered using volatile solvents due to their poor coordination with...
Conspectus:
In the ever-increasing renewable-energy demand scenario, developing new photovoltaic technologies is important, even in the presence of established terawatt-scale silicon technology. Emerging photovoltaic technologies play a crucial role in diversifying material flows while expanding the photovoltaic product portfolio, thus enhancing s...
Perovskite nanocrystals (NCs) have garnered increasing attention as light-emitting materials owing to their high photoluminescence quantum yields (PLQY) and narrow full width at half-maximum (fwhm). However, the poor stability hinders their practical application in displays. In this work, we investigate the photostability of FAPbBr3 NCs with the mo...
Achieving high-performance perovskite photovoltaics, especially in ambient air relies heavily on optimizing process parameters. However, traditional manual methods often struggle to effectively control the key variables. This inherent challenge requires a paradigm shift toward automated platforms capable of precise and reproducible experiments. Her...
The development of a robust quasi-ohmic contact with minimal resistance, good stability and cost-effectiveness is crucial for perovskite solar cells. We introduce a generic approach featuring a Lewis-acid layer sandwiched between dopant-free semicrystalline polymer and metal electrode in perovskite solar cells, resulting in an ideal quasi-ohmic con...
Interface engineering is crucial to achieving stable perovskite photovoltaic devices. A versatile approach is developed to tailor interface properties via integrating co-assembled monolayers (co-SAMs) at the p-type buried interface and by capping a two-dimensional (2D) perovskite layer at the n-type upper interface with vacuum quenching. Optimized...
Obtaining highly stable metal-halide perovskites is crucial for the commercialization of perovskite solar cells. However, current methods for evaluating perovskite stability mainly rely on a time-consuming and resource-intensive aging process. Here, we demonstrate a spectral learning-based methodology that enables the prediction of perovskite stabi...
The instability of perovskite absorbers under various environmental stressors is the most significant obstacle to widespread commercialization of perovskite solar cells. Herein, we study the evolution of crystal structure and microstrain present in naked triple-cation mixed CsMAFA-based perovskite films under heat, UV, and visible light (1 Sun) con...
In article number 2302594, Jiyun Zhang, Yicheng Zhao, Christoph J. Brabec and co-workers develop a machine-learning-guided automated platform, the SPINBOT, to optimize solution-processed perovskite thin films. The platform efficiently explores an intricate multi-dimensional parameter space to produce high-quality and reproducible films. As a result...
Since the earliest days of liquid-phase epitaxy (LPE) research, substrate stability has been a prerequisite for investigating nucleation and epitaxial growth. For flux- and melt-growth LPE, soluble substrates have always been viewed as problematic and difficult. However, solution-growth LPE transforms this disadvantage into a benefit by facilitatin...
Simultaneously optimizing the processing parameters of functional thin films remains a challenge. The design and utilization of a fully automated platform called SPINBOT is presented for the engineering of solution‐processed functional thin films. The SPINBOT is capable of performing experiments with high sampling variability through the unsupervis...
Introducing large organic cations to form reduced-dimensional (quasi-2D) perovskites has proven to be effective in stabilizing three-dimensional perovskites. In this study, we synthesized 28 Ruddlesden–Popper-type quasi-2D perovskites using four aromatic-based cations (phenylmethylammonium (PMA), phenethylammonium (PEA), phenylpropylammonium (PPA),...
High-throughput synthesis of solution-processable structurally variable small-molecule semiconductors is both an opportunity and a challenge. A large number of diverse molecules provide a possibility for quick material discovery and machine learning based on experimental data. However, the diversity of the molecular structure leads to the complexit...
Dumbbell‐shaped systems based on PAHs‐BODIPY‐triarylamine hybrids TM‐(01‐04) are designed as novel and highly efficient hole‐transporting materials for usage in planar inverted perovskite solar cells. BODIPY is employed as a bridge between the PAH units, and the effects of the conjugated π‐system's covalent attachment and size are investigated. Flu...
Mixed lead and tin (Pb/Sn) hybrid perovskites exhibit a great potential in fabricating all‐perovskite tandem devices due to their easily tunable bandgaps. However, the energy deficit and instability in Pb/Sn perovskite solar cells (PSCs) constrain their practical applications, which renders defect passivation engineering indispensable to develop hi...
Cradle-to-cradle recycling plays an important role in resolving one of the major upcoming challenges for photovoltaics in the energy transition-resource management. As photovoltaic production continues to grow, it absorbs a vast amount of resources. Cradle-to-cradle recycling is essential to keep these resources available perpetually and minimize w...
High-throughput synthesis of solution-processable structurally variable small-molecule semiconductors is both an opportunity and a challenge. A large number of diverse molecules provide a possibility for quick material discovery and machine learning based on experimental data. However, the diversity of molecular structure leads to the complexity of...
Organic solar cells (OSCs) now approach power conversion efficiencies of 20%. However, in order to enter mass markets, problems in upscaling and operational lifetime have to be solved, both concerning the connection between processing conditions and active layer morphology. Morphological studies supporting the development of structure–process–prope...
We report the design and utilization of a fully automated platform called SPINBOT for the engineering of solution-processed functional thin films. The SPINBOT is capable of performing experiments with high sampling variability through the unsupervised processing of hundreds of substrates with exceptional experimental control. We demonstrate the uni...
Lead-Tin perovskite solar cells (Pb/Sn PSCs) are limited by the intrinsic instability of Sn(II), which tends to oxidize forming Sn vacancies in perovskite films. Herein, a Lewis base β-guanidinopropionic acid (GUA) and hydrazinium iodide (HAI) are introduced to effectively passivate the perovskite bulk and surface, respectively. The synergistic app...
Epitaxial growth methods usually need dedicated equipment, high energy consumption to maintain pure vacuum conditions and evaporation of source materials, and elevated substrate temperatures. Solution epitaxial growth requires nothing of that but is rarely used because the achieved microstructures are of low quality, not homogeneous, and finally ex...
Reduced‐dimensional (2D or quasi‐2D) perovskites have recently attracted considerable interest due to their superior long‐term stability. The nature of the intercalating cations plays a key role in determining the physicochemical properties and stability of the quasi‐2D perovskites. Here, the thermal stability of a series of 2D Ruddlesden−Popper (R...
Rational design and engineering of top interface layers with combined properties of effective passivation, high thermal‐ and photo‐stability are effective methods to advance the commercialization of perovskite photovoltaics. Here, we develop an innovative anode interface combination based on alcohol‐dispersed poly(3‐hexylthiophene‐2,5‐diyl) (P3HT)...
The long-term stability of perovskite solar cells remains a challenge. Both the perovskite layer and the device architecture need to endure long-term operation. Here we first use a self-constructed high-throughput screening platform to find perovskite compositions stable under heat and light. Then, we use the most stable perovskite composition to i...
Identification and investigation of strain at buried interfaces in halide perovskite photovoltaics are crucial for directing research on the performance and stability of perovskite solar cells. In this work, we find a gradual shift in the band gap of up to 60 meV over a perovskite layer thickness of 300 nm caused by interfacial strain. This graded...
Stability of perovskite-based photovoltaics remains a topic requiring further attention. Cation engineering influences perovskite stability, with the present-day understanding of the impact of cations based on accelerated ageing tests at higher-than-operating temperatures (e.g. 140°C). By coupling high-throughput experimentation with machine learni...
Light-induced halide segregation limits the bandgap tunability of mixed-halide perovskites for tandem photovoltaics. Here we report that light-induced halide segregation is strain-activated in MAPb(I1−xBrx)3 with Br concentration below approximately 50%, while it is intrinsic for Br concentration over approximately 50%. Free-standing single crystal...
Alloying structurally similar perovskites to form mixed-cation lead iodide perovskites, e.g., CsxFA(1−x)PbI3, MAxFA(1−x)PbI3, and CsxMAyFA(1−x−y)PbI3, could improve the performance of perovskite-based solar cells and light-emitting diodes. However, a phase diagram of them and a clear understanding of the underlying atomic-scale mechanism are still...
Cerium doped gadolinium yttrium gallium aluminum garnet ceramics, GYGAG:Ce for short, have drawn a lot of attention and showed a very promising application in medical CT detectors. This mainly attributes to their excellent scintillation properties, such as high light output, low afterglow, fast decay and high x-ray stopping power. In order to provi...
Rare earth ions possess highly conductive, magnetic, electrochemical and luminescent properties, multiple valence electrons and long lifetime of excited state, thus could be alternatives as dopant to tune and promote the cathode interlayer property in solar cells. In this work, we study the modification of cathode interlayer by rare earth ion dopin...
Cerium doped gadolinium gallium aluminum garnet ceramics (GGAG:Ce) is promising in applications such as medical imaging, high power WLEDs and other high energy radiation detection due to their excellent and unique combination of chemical and physical properties. Partial substitution of gadolinium with yttrium can improve the optical and scintillati...
A novel banded structure ceramic phosphor has been fabricated in this research. This structure provides a convenient and effective method in regulating full spectrum. It has the advantage of being able to adjust the intensity of all three primary colors independently, regardless of the mutual absorption among different active ions.
Cerium doped gadolinium gallium aluminum garnet (GGAG:Ce) ceramic precursors have been synthesized with an ultrasonic chemical co-precipitation method (UCC) and for comparison with a traditional chemical co-precipitation method (TCC). The effect of ultra-sonication on the morphology of powders and the transmittance of GGAG:Ce ceramics are studied....
Among the aluminate garnet materials, cerium doped gadolinium gallium aluminum garnet ceramics (GGAG:Ce) have shown great performance advantages, which suggests their promising applications in medical imaging, high energy rays detection and high power LED lighting. The goal of this work is to raise the thermostability of GGAG:Ce by means of partial...
