Eugene A Katz

• Prof.
• Professor (Full) at Ben-Gurion University of the Negev

This study examines the optoelectronic properties of nitride‐based multiquantum well solar cells, which are gaining importance in hybrid thermal‐photovoltaic applications due to their resilience to high temperatures. The investigation focuses on the current characteristics of these devices under six distinct illumination conditions. A self‐consiste...

The power-conversion efficiency (PCE) of perovskite solar cells (PSCs) has exceeded in 2024 the theoretical single-junction Shockley–Queisser limit of 33.7% with the perovskite/silicon tandem version. The commercialization of the technology is now a reality with the PV industry demonstrating its first commercial products. Many companies have shown...

Perovskite solar cells (PSCs) are expected to transform the photovoltaic market; however, their unproven operational stability requires urgent attention, particularly accelerated aging tests. Currently, illumination is the primary stressor in such tests. In this work, we present an accelerated aging procedure consisting of prolonged forward biasing...

The critical challenge for the commercialization of perovskite solar cells (PSCs) is their operational stability. PSCs’ outdoor operation exposes the cells to a combination of stress factors that are difficult to reproduce by indoor testing due to diurnal and seasonal variations. This highlights the need for outdoor testing under operational condit...

Upconversion-the absorption of two or more photons resulting in radiative emission at a higher energy than the excitation-has the potential to enhance the efficiency of solar energy harvesting technologies, most notably photovoltaics. However, the required ultra-high light intensities and the narrow absorption bands of lanthanide ions limit efficie...

Perovskite solar cells represent one of the most promising emerging photovoltaic technologies due to their high power conversion efficiency. However, despite of the huge progress made not only in terms of the efficiency achieved, but also fundamental understanding of relevant physics of the devices and issues which affect their efficiency and stabi...

Operational stability keeps perovskite photovoltaics from being massively introduced in the energy market. Stability assessment studies can last for months or even years. Concentrated solar light to accelerate degradation of perovskite thin films (PTF) [1] and solar cells (PSC) [2] has already been demonstrated. Photoluminescence (PL) can be the mo...

Cheaper technologies for the widespread use of solar energy are of paramount importance for the sustainable generation of energy. In this scenario, hybrid and organic photovoltaics play an important role. More work is necessary, however, to improve the durability (stability) and scalability of these solar devices. This Voices piece asks: What do hy...

While high efficiencies were achieved for organic photovoltaic (OPV) cells, the commercialization of this technology requires addressing the challenge of long-term device stability. The application of stabilizers is one of...

Motivated by possible application of InGaN/GaN multi-quantum well solar cells in hybrid concentrated photovoltaic / solar thermal power conversion systems, we have analyzed the temperature and intensity dependence of the open-circuit voltage of such devices up to 725 K and more than 1000 suns. We show that the simple ABC model routinely used to ana...

The power conversion efficiency of the market‐dominating silicon photovoltaics approaches its theoretical limit. Bifacial solar operation with harvesting additional light impinging on the module back and the perovskite/silicon tandem device architecture are among the most promising approaches for further increasing the energy yield from a limited a...

The power conversion efficiency of the market-dominating silicon photovoltaics approaches its theoretical limit. Bifacial solar operation with harvesting additional light impinging on the module back and the perovskite/silicon tandem device architecture are among the most promising approaches for further increasing the energy yield from a limited a...

Comparison between different laboratories on long‐term stability analyses of perovskite solar cells (PSCs) is still lacking in the literature. This work presents the results of an inter‐laboratory study carried out between 5 laboratories from 4 countries. Carbon‐based PSCs were prepared by screen printing, encapsulated and sent to different laborat...

Today the term ‘ perovskite ’ is used to designate the crystalline structure of a wide variety of ABX3 ionic compounds. However, historically this name was used for a specific material, having been coined for a mineral, calcium titanate (CaTiO3). This mineral was discovered in the Ural Mountains, Russia . The first sample of the mineral was transfe...

One of the major challenges in the field of organic photovoltaics is associated with high-throughput manufacturing of efficient and stable organic solar cells. Practical realization of technologies for production of large-area organic solar cells requires the development of novel materials with a defined combination of properties ensuring sufficien...

Improving the long-term stability of perovskite solar cells is critical to the deployment of this technology. Despite the great emphasis laid on stability-related investigations, publications lack consistency in experimental procedures and parameters reported. It is therefore challenging to reproduce and compare results and thereby develop a deep u...

We report on simulations of idealized bifacial perovskite/silicon tandem solar cells which are placed in a large PV field. These simulations are used to perform energy-yield optimizations for two- and four-terminal tandem cell configurations.

The research on halide perovskites is in its peak activity at the moment due to the material's potential application in photovoltaics. It is well known that slow processes, from seconds to minutes, are very significant in perovskite films and devices as compared to conventional photovoltaic materials. The kinetics of photo-luminescence (PL) is info...

Degradation rates in perovskite solar cells (PSC) were previously shown to be bias‐dependent, however little is known about the mechanisms and driving factors that account for such degradation. Herein we demonstrate that stability study under concentrated sunlight is a powerful experimental methodology to investigate bias‐dependent PSC degradation...

We report a cooperative study conducted between different laboratories to investigate organic solar cell degradation with respect to P3HT material properties and different solar cell architectures. Various batches of P3HT were collected from different suppliers reflecting commercial availability as well as properties variability. Among the material...

Initial stages of photo‐degradation of CH3NH3PbI3 (MAPbI3) thin films prior to any significant change in light absorption are studied in experiments with independent control of sample temperature and intensity of concentrated sunlight from 50 to 500 suns. Photo‐stability of the MAPbI3 film is revealed to be extremely sensitive to the sample tempera...

Encapsulated organic solar cells often show a burn-in behaviour under illumination. This burn-in manifests itself as a rapid performance loss followed by a much slower progression of the degradation. Here we investigate the burn-in for PCDTBT:PC 70 BM solar cells under a wide range of illumination intensities. We find that increasing the sunlight c...

Molecularly engineered non-covalent hybrids comprising carbon nanotubes (CNTs) and fullerenes may combine the electronic and mechanical properties of CNTs with the optical and excellent electron acceptor characteristics of the fullerenes. As was demonstrated by us in a previous study, a two-step process comprising solution processing of multi-wall...

We report on utilizing free-standing hybrid perylenediimide/carbon nanotube (PDI /CNT) films fabricated in air as back contacts for fully inorganic perovskite solar cells (Glass/FTO/dense TiO2/mesoporous TiO2/CsPbBr3/back electrode). The back contact electrode connection is performed by film transfer rather than by vacuum deposition or by wet proce...

Understanding device instability mechanisms in halide perovskite solar cells (PSCs) is the key aspect to achieve a breakthrough in photovoltaics. One of the puzzling questions in this regard is electrical bias-dependent degradation of PSCs. Several mechanisms have been suggested to explain the effect, but none are sufficient to embrace all observat...

Photo-luminescence (PL) of the perovskite is a sensitive optical property directly linked to the performance of solar cells. Although it has been traditionally used to probe and monitor carrier recombination under laser excitation, photovoltaic operation intuitively implies the sun for photo-excitation. For this reason, we have developed a new conf...

A tetra- n -butoxy zinc phthalocyanine ( n -BuO) 4 ZnPc has been synthesized in a single step, starting from commercial precursors, and easily purified. The molecule can be solution processed to form an effective and inexpensive hole transport layer for organic and perovskite solar cells. These appealing features are suggested by the results of a s...

High performance photovoltaic polymers bearing crosslinkable function together with a photo-robust conjugated backbone are highly desirable for organic solar cells to achieve both high device efficiency and long-term stability. In this paper, a family of such polymers is reported based on poly[(2,5-bis(2-hexyldecyloxy)phenylene)-alt-(5,6-difuoro-4,...

This work is part of the interlaboratory collaboration to study the stability of organic solar cells containing PCDTBT polymer as a donor material. The varieties of the OPV devices with different device architectures, electrode materials, encapsulation, and device dimensions were prepared by seven research laboratories. Sets of identical devices we...

Stability of organic solar cells with PCDTBT donor polymer: An interlaboratory study – ERRATUM - Laura Ciammaruchi, Ricardo Oliveira, Ana Charas, Tulus, Elizabeth von Hauff, Giuseppina Polino, Francesca Brunetti, Rickard Hansson, Ellen Moons, Miron Krassas, George Kakavelakis, Emmanuel Kymakis, José G. Sánchez, Josep Ferre-Borrull, Lluis F. Marsal,...

Hybrid solar photovoltaic (PV)/thermal power systems offer the possibility of dispatchable, affordable and efficient solar electricity production - the type of transformative innovation needed for solar to realize high grid penetration. The PV sub-system enjoys high efficiency, and the thermal sub-system can ensure uninterrupted power delivery via...

Post‐deposition processing of organolead halide films, by exposure to alkyl amine vapor and composition transformation, is an attractive approach for the formation of high‐quality and large‐scale perovskite films of desired compositions. However, the generalization of such composition transformation requires further understanding of the mechanism o...

Herein, the use of highly concentrated sunlight for materials science research is reviewed. Specific research directions include: (1) the generation of inorganic nanostructures, some of which had eluded experimental realization with conventional synthetic processes, and (2) elucidating the processes governing the degradation of organic and perovski...

The development of hybrid organic-inorganic halide perovskite solar cells (PSCs) that combine high performance and operational stability is vital for implementing this technology. Recently, reversible improvement and degradation of PSC efficiency have been reported under illumination-darkness cycling. Quantifying the performance and stability of ce...

Donor–acceptor (D–A) conjugated polymers bearing non-covalent configurationally locked backbones have a high potential to be good photovoltaic materials. Since 1,4-dithienyl-2,5-dialkoxybenzene (TBT) is a typical moiety possessing intramolecular S…O interactions and thus a restricted planar configuration, it was used in this work as an electron-don...

The operational stability of perovskite solar cells (PSCs) remains one of the limiting factors of their commercial implementation. We studied the long-term outdoor stability, as well as the dynamics of the cells' degradation, under constant, simulated sunlight indoor and their recovery in the dark, of ITO/SnO2/ Cs0.05((CH3NH3)0.15(CH(NH2)2)0.85)0.9...

Encapsulated CH 3 NH 3 PbI 3 films, the 'work horse' of the organic-inorganic perovskite-based photovoltaics, grown by one step-and two step-deposition methods, were used to study the effect of the film preparation method on their photostability. Time dependent light absorption decay under exposure to concentrated sunlight was used to estimate the...

Multi-junction (MJ) solar cells are one of the most promising technologies achieving high sunlight to electricity conversion efficiency. Resistive losses constitute one of the main underlying mechanisms limiting their efficiency under high illumination. In this paper, we study, by numerical modeling, the extent to which a fine-tuning of the differe...

Exohedral van der Waals (vdW) hybrids comprising pristine carbon nanotubes (CNTs) and C60 fullerenes are expected to enable the engineering of carbonaceous materials with tunable physical and chemical properties due to the unperturbed sp² hybridization of the comprising allotropes. In spite of theoretical predictions, experimental realization of ex...

The development of high temperature CPV/thermal (CSP) hybrid systems appears to be a promising route to improve the overall solar to electricity conversion efficiency. Moreover, such systems would not only use the residual heat stemming from the unconverted fraction of the incident solar radiation in PV cells, but they would also provide the advant...

This paper presents a systematic study of the influence of electron-transport materials on the operation stability of the inverted perovskite solar cells under both laboratory indoor and the natural outdoor conditions in the Negev desert. It is shown that all devices incorporating a Phenyl C61 Butyric Acid Methyl ester ([60]PCBM) layer undergo rapi...

The application of luminescent down shifting (LDS) layers as alternative UV filters for CH3NH3PbI3(1-x)Cl3x perovskite solar cell (PSC) devices is reported. A combination of photo-absorption measurements and of device decay measurements during light soaking are used to verify the stability. The application of a UV filter or LDS layer was able to si...

Halide perovskites are widely studied due to their potential applications in solar cells. Despite the remarkable success in increasing perovskite solar cell efficiency, the underlying photophysical processes remain unclear. To cover this gap, we studied temperature,spectral, and light intensity dependence of photoconductivity of CH3NH3PbI3 films in...

We present a systematic comparative study of the intrinsic photochemical stability of several fullerene-polymer systems under the natural outdoor conditions in the Negev desert. It has been shown, in particular, that light-induced dimerization of the [60]fullerene derivatives is irrelevant to the degradation behavior of the solar cells incorporatin...

The confluence of high-temperature (~1600–3200 K) flameless combustion chambers and vertical-junction (VJ) photovoltaics creates the possibility of ultra-compact high-efficiency thermophotovoltaic (TPV) generators. The actively-cooled cells can be sited at the chamber's aperture without contaminating or damaging them. The flux density, however, is...

The photochemical stability of encapsulated films of mixed halide perovskites with a range of MAPb(I1-x Brx )3 (MA=methylammonium) compositions (solid solutions) was investigated under accelerated stressing using concentrated sunlight. The relevance of accelerated testing to standard operational conditions of solar cells was confirmed by comparison...

Electron-filtering compound buffer layers (EF-CBLs) improve charge extraction in organic photovoltaic cells (OPVs) by blending an electron-conducting fullerene with a wide energy gap exciton-blocking molecule. It is found that devices with EF-CBLs with high glass transition temperatures and a low crystallization rate produce highly stable morpholog...

Photochemical stability of encapsulated films of mixed halide perovskites with a range of MAPb(I1-xBrx)3 compositions (solid solutions) was investigated under accelerated stressing using concentrated sunlight. Evolution of light absorption and the corresponding structural modifications in the films were recorded by UV-vis spectroscopy and X-ray dif...

The temperature dependence of the principal photovoltaic parameters of perovskite photovoltaics is studied. The recombination activation energy is in good agreement with the perovskite's bandgap energy, thereby placing an upper bound on open-circuit voltage. The photocurrent increases moderately with temperature and remains high at low temperature,...

The principle remaining challenge in the research area of organic photovoltaic (OPV) materials is to develop solar cells that combine high efficiency, stability and reproducibility. Here, we demonstrate an experimental strategy which has successfully addressed this challenge. We produced a number of samples of the highly efficient PTB7 polymer with...

We report the first outdoor study of the intrinsic photochemical stability of a series of conjugated polymers encapsulated in an inert atmosphere and exposed to natural sunlight illumination conditions in the Negev Desert. The photoinduced aging effects resulting in the modification of the chemical structures of the materials and the appearance of...

The proof of concept of using luminescent down shifting (LDS) layers as alternative UV filters for P3HT: PCBM OPVs is demonstrated using a lanthanide-based metal complex. The results are verified using a combination of indoor light soaking, with single cell devices, and outdoor performance monitoring, using a 16-cell monolithically connected OPV mo...

An experimental demonstration of the combined photovoltaic (PV) and thermoelectric conversion of concentrated sunlight (with concentration factor, X, up to ∼300) into electricity is presented. The hybrid system is based on a multi-junction PV cell and a thermoelectric generator (TEG). The latter increases the electric power of the system and dissip...

Efficiency enhancement of bulk heterojunction (BHJ) organic solar cells by means of the plasmonic effect is investigated by using finite-difference time-domain (FDTD) optical simulations combined with analytical modeling of exciton dissociation and charge transport efficiencies. The proposed method provides an improved analysis of the cell performa...

Can C60 layer cover a surface of single-wall carbon nanotube (SWCNT) forming an exohedral pure-carbon hybrid with only VdW interactions? The paper addresses this question and demonstrates that the fullerene shell layer in such a bucky-corn structure can be stable. Theoretical study of structure, stability and electronic properties of the following...

Stabilities of ITO-containing and ITO-free organic solar cells were investigated under simulated AM 1.5G illumination and under concentrated natural sunlight. In both cases ITO-free devices exhibit high stability, while devices containing ITO show degradation of their photovoltaic performance. The accelerated degradation under concentrated sunlight...

We report on accelerated degradation testing of MAPbX3 films (X = I or Br) by exposure to concentrated sunlight of 100 suns and show that the evolution of light absorption and the corresponding structural modifications are dependent on the type of halide ion and the exposure temperature. One hour of such exposure provides a photon dose equivalent t...

We report on the interrelationship between luminescent, non-linear optical and photo-sensitizing properties of aggregates of inorganic chromophores (PbS, C60, SWCNT, and C60@SWCNT nanopeapods) in presence of polymers against the aggregates defectiveness degree.

Accurate characterization and reporting of organic photovoltaic (OPV) device performance remains one of the important challenges in the field. The large spread among the efficiencies of devices with the same structure reported by different groups is significantly caused by different procedures and equipment used during testing.The presented article...

Power conversion efficiency of hybrid inorganic-organic metal halide perovskite-based photovoltaic devices has recently reached ~18% [1,2].A significant challenge facing the development of such cells is combining high efficiency and operational stability. However, the published data about degradation mechanisms and stability of perovskite-based mat...

We have demonstrated OPV accelerated degradation studies using concentrated sunlight, where the atmosphere, temperature and illumination intensity were independently controlled. Testing various schemes for controlling the sample temperature under concentrated sunlight showed that heating of P3HT:PCBM was caused by photons at the absorbed wavelength...

We present experimental evidence for improving the open-circuit voltage – and thereby efficiency - of photovoltaics via the external recycling of photon emission. This strategy is equivalent to limiting the angular extent of photon emission - effective only in photovoltaics with high external luminescent efficiency. This is why the effect has not b...

Experimental evidence of enhancing the performance of ultra-efficient solar cells by external recycling of photon emission is presented – predicated on the strategy of increasing cell open-circuit voltage by reducing radiative recombination. It is equivalent to restricting the angular range of photon emission, and can only be effective in photovolt...

We report experimental results for the effect of irradiance (from 12 up to 8600 suns) on the temperature coefficients of the key performance parameters of multijunction concentrator solar cells, with a flash‐like, real‐sun optical system. Particular attention is paid to the time scales and magnitudes of junction heating, hence the degree to which t...

A novel multiple-bandgap multi-terminal vertical-junction (side-illumination) architecture for concentrator solar cells is proposed and simulated, wherein each stacked sub-cell operates at its own maximum power point, without the need for tunnel diodes, current matching, lattice matching, metallization grids or spectrum splitting. Practical impleme...

Conjugated polymers and carbon nanotubes (CNTs) are important constituents of modern functional hybrid materials. Their utilization as photoactive layers in organic solar cells requires better understanding of the relation between the structure and composition of the hybrids and their photovoltaic efficiency. While fullerenes‐conjugated polymer hyb...

Large-area organic solar cells are known to suffer from a major efficiency decrease which originates from the combination of a voltage drop across the front electrode and the voltage-dependent photocurrent. In this letter, we demonstrate this efficiency loss on large area, indium tin oxide free cells with a hexagonal current collecting front grid,...

We suggest to use concentrated sunlight for accelerated studies of light-induced mechanisms in the degradation of organic photovoltaics (OPV) based on the polymer (P3HT)/fullerene (PCBM) bulk heterojunctions. Two particular cases of the degradation are reported.

Measurements of tandem GaInAsP/InGaAs concentrator solar cells are presented and demonstrate how the short-circuit current of multijunction cells can shift from the higher-current subcell to the lower-current subcell as irradiance increases. Basic modeling shows how this can occur for cells that exhibit a noticeably non-zero slope in the low-voltag...

A flash-like, real-sun optical system has been used to experimentally measure the effect of irradiance (from 11 up to 8,600 suns) on the temperature coefficients of the key performance parameters of multijunction concentrator solar cells. Particular attention is paid to the time scales and magnitudes of junction heating, hence the degree to which t...

The basis for the temperature dependence of the principal performance parameters of single and multi-junction concentrator solar cells is examined, focusing on the impact of bandgap and irradiance. The analysis of cells in the radiative limit establishes fundamental bounds. A quasi-empirical model yields predictions consistent with available data....

Electrospun sub-micron fibers containing conjugated polymer (poly(3-hexylthiophene), P3HT) with a fullerene derivative, phenyl-C61-butyric acid methylester (PCBM) or a mixture of PCBM and single-walled carbon nanotubes (SWCNTs) were studied by light-induced electron paramagnetic resonance spectroscopy. The results provide experimental evidence of e...

We present a simple post-processing treatment, which dramatically improves the electrical properties of inverted geometry bulk-heterojunction organic solar cells, by enhancing functionality of the zinc-oxide hole blocking layer. The results show that inherent problems associated with the ZnO layer (e.g. shunting and J–V inflection points) are of th...

a b s t r a c t A new encapsulation method for organic solar cells has been tested on flexible solar modules and cells embedded in polyurethane, sandwiched between a tempered glass plate and a polycarbonate plate. Panels, each containing 10 organic solar modules/cells, were fabricated and installed for outdoor exposure in eight different countries...