Publications by Type: Journal Article

2018
Lior Iagher and Etgar Lioz. 1/10/2018. “The Effect of Cs on the Stability and Photovoltaic Performance of 2D/3D Perovskite-based Solar Cells.” ACS Energy Lett., DOI: 10.1021/acsenergylett.7b01196. the_effect_of_cs_on_the_stability_and_photovoltaic_performance.pdf
Etgar Lioz. 1/2018. “The merit of perovskite’s dimensionality; can this replace the 3D halideperovskite?.” Energy Environ. Sci., 2018: DOI: 10.1039/C7EE03397D. c7ee03397d.pdf
2017
Tufan Ghosh, Sigalit Aharon, Etgar Lioz, and Sanford Ruhman. 12/5/2017. “Free carrier emergence and onset of electron-phononcoupling in methylammonium lead halide perovskite films.” Journal of the American Chemical Society, DOI: 10.1021/jacs.7b09508. free_carrier_emergence_and_onset_of_electron-phonon_coupling_in_methylammonium_lead_halide_perovskite_films.pdf
Daniel Amgar, Małgorzata Wierzbowska, Vladimir Uvarov, Vitaly Gutkin, and Etgar Lioz. 10/23/2017. “Novel Rubidium lead chloride nanocrystals: Synthesis and characterization.” Nano Futures, 1: 021002. novel_rubidium_lead_chloride_nanocrystals.pdf
Stav Rahmany, Michael Layani, Shlomo Magdassi, and Etgar Lioz. 9/24/2017. “Fully functional semi-transparent perovskitesolar cell fabricated at ambient air.” Energy & Fuels, DOI: 10.1039/c7se00383h. fully_functional_semi-transparent.pdf fully_functional.png
Ravi K. Misra, Bat-El Cohen, Lior Iagher, and Etgar Lioz. 8/28/2017. “Low-Dimensional Organic–Inorganic Halide Perovskite:Structure, Properties, and Applications.” ChemSusChem, 2017,10: 3712 – 3721. low_dimensional_organic_inorganic.png low-dimensional_organic-inorganic_halide_perovskite.pdf
Bat-El Cohen, Malgorzata Wierzbowska, and Etgar Lioz. 8/10/2017. “High efficiency quasi 2D lead bromide perovskitesolar cells using various barrier molecules.” Sustainable Energy & Fuels, 2017,1: 1935–1943. high_efficiency_quasi_2d_lead_bromide_perovskite.pdf high_efficiency_quasi_2d_1.png
Y. Huang, S. Aharon, A. Rolland, L. Pedesseau, O. Durand, L. Etgar, and J. Even. 5/19/2017. “Influence of Schottky contact on the C-V and J-V characteristicsof HTM-free perovskite solar cells.” EPJ Photovoltaics, 2017,8: 85501.Abstract

Abstract The influence of the Schottky contact is studied for hole transport material (HTM) free
CH3NH3PbI3 perovskite solar cells (PSCs), by using drift-diffusion and small signal models. The basic
current-voltage and capacitance-voltage characteristics are simulated in reasonable agreement with experimental
data. The build in potential of the finite CH3NH3PbI3 layer is extracted from a Mott-Schottky
capacitance analysis. Furthermore, hole collector conductors with work-functions of more than 5.5 eV are
proposed as solutions for high efficiency HTM-free CH3NH3PbI3 PSCs.

influence_of_schottky_contact_on_the_c-v_and_j-v_characteristics.pdf
Chongwen Li, Yuanyuan Zhou, Yue Chang Li Wang, Yingxia Zong, Etgar Lioz, Guanglei Cui, Nitin P. Padture, and Shuping Pang. 5/19/2017. “Methylammonium-Mediated Evolution of Mixed-Organic-CationPerovskite Thin Films: A Dynamic Composition-Tuning Process.” Angew. Chem. Int. Ed., 2017,56: 7674 –7678. methylammonium.png methylammonium-mediated_evolution_of_mixed-organic-cation.pdf
Yue Chang, Li Wang, Jiliang Zhang, Zhongmin Zhou, Chongwen Li, Bingbing Chen, Etgar Lioz, Guanglei Cui, and Shuping Pang. 2/10/2017. “CH3NH2 gas induced (110) preferred cesiumcontainingperovskite films with reduced PbI6octahedron distortion and enhanced moisturestability.” J. Mater. Chem. A, 2017,5: 4803–4808.Abstract

We report here the discovery of a fancy interaction between cesium iodide (CsI) and methylamine (CH3NH2) due to the presence of the hydrogen bond. The formed CsI$xCH3NH2 is a liquid phase, which facilitates the large scale fabrication of highly uniform cesium-containing perovskite films with strong (110) preferred orientation by the CH3NH2 gas healing process. With this method, at most 10% nonpolar Cs cations could fully dope into the crystal lattice and extremely enhance the interaction of the inorganic framework with a more
symmetrical PbI6 octahedron, resulting in obvious improvement in moisture stability under continuous illumination.

ch3nh2_gas_induced_110_preferred_cesiumcontaining.pdf ch3.png
Bat-El Cohen, Małgorzata Wierzbowska, and Etgar Lioz. 2/3/2017. “High Efficiency and High Open Circuit Voltage in Quasi 2DPerovskite Based Solar Cells.” Advanced Functional Materials, 2017: 1604733.Abstract

An important property of hybrid layered perovskite is the possibility to reduce
its dimensionality to provide wider band gap and better stability. In this work,
2D perovskite of the structure (PEA)2(MA)n–1PbnBr3n+1 has been sensitized,
where PEA is phenyl ethyl-ammonium, MA is methyl-ammonium, and using
only bromide as the halide. The number of the perovskite layers has been
varied (n) from n = 1 through n = ∞. Optical and physical characterization
verify the layered structure and the increase in the band gap. The photovoltaic
performance shows higher open circuit voltage (Voc) for the quasi 2D perovskite
(i.e., n = 40, 50, 60) compared to the 3D perovskite. Voc of 1.3 V without
hole transport material (HTM) and Voc of 1.46 V using HTM have been
demonstrated, with corresponding efficiency of 6.3% and 8.5%, among the
highest reported. The lower mobility and transport in the quasi 2D perovskites
have been proved effective to gain high Voc with high efficiency, further
supported by ab initio calculations and charge extraction measurements. Bromide
is the only halide used in these quasi 2D perovskites, as mixing halides
have recently revealed instability of the perovskite structure. These quasi 2D
materials are promising candidates for use in optoelectronic applications that
simultaneously require high voltage and high efficiency.

high_efficiency_and_high_open_circuit_voltage.png hight_efficiency_and_hight.pdf
Daniel Amgar, Avigail Stern, Dvir Rotem, Danny Porath, and Etgar Lioz. 1/17/2017. “Tunable Length and Optical Properties of CsPbX3 (X = Cl, Br, I)Nanowires with a Few Unit Cells.” Nano Letters, 2017, 17: 1007−1013.Abstract

Perovskite nanostructures, both hybrid organo−metal
and fully inorganic perovskites, have gained a lot of interest in the past
few years for their intriguing optical properties in the visible region. We
report on inorganic cesium lead bromide (CsPbBr3) nanowires (NWs)
having quantum confined dimensions corresponding to 5 unit cells. The
addition of various hydrohalic acids (HX, X = Cl, Br, I) was found to
highly affect the NW length, composition, and optical properties.
Hydrochloric (HCl) and hydroiodic (HI) acids mixed in the reaction
solution influence the crystal structure and optical properties and
shorten the NWs, while the hydrobromic acid (HBr) addition results
solely in shorter NWs, without any structural change. The addition of HX increases the acidity of the reaction solution, resulting
in protonation of the oleylamine ligands from oleylamine into oleyl-ammonium cations that behave similarly to Cs+ during
crystallization. Therefore, the positions of the Cs+ at the growing surface of the NWs are taken by the oleyl-ammonium cations,
thus blocking further growth in the favored direction. The emission of the NWs is tunable between ∼423−505 nm and possesses
a potential in the optoelectronic field. Moreover, electrical conductivity measurements

tunable_length_and_optical_properties_of_few.png tunable_length_and_optical_properties_of_cspbx3.pdf
2016
Hadas Naor, Yiftach Divon, Lior Iagher, Etgar Lioz, and David Avnir. 11/14/2016. “Conductive molecularly doped gold films.” J. Mater. Chem. C, 2016,4: 11548--11556.Abstract

We describe a general synthesis of conductive gold thin films doped with entrapped organic molecules,
and demonstrate, for the first time, the immobilization of a redox couple within an electrode in a single
step. The resulting film is of dual properties: conductivity arising from the gold, and redox behavior
originating from the entrapped molecule. Faster electron-transfer rates are found for the entrapped
case, compared to adsorption. The conductivity of the film affects the organic molecule–metal interactions,
as seen in resistivity measurements, in Raman spectroscopy of the metal-entrapped molecules and from
a remarkable red shift of 30 nm in emission spectroscopy. Doping is found to affect the work function
of gold. Thin conductive doped metal films are of relevance to a variety of applications such as
electrochemical detectors, electrode materials for electrochemical impedance spectroscopy, micro and
nano electronics interconnects for packaging and for printed circuit boards. The ability to fine-tune the
work function opens the possibility to design the desired energy level gaps for optoelectronic applications
such as light emitting diodes (LEDs), solar cells and transistors.

conductive_molecularly_doped_gold_films.pdf conductive_molecularly_doped_gold_films.png
Shany Gamliel, Inna Popov, Bat-El Cohen, Vladimir Uvarov, and Etgar Lioz. 11/2016. “Structural and Quantitative Investigation of Perovskite Pore Filling in Mesoporous Metal Oxides.” Crystals, 2016, 6: 149.Abstract

In recent years, hybrid organic–inorganic perovskite light absorbers have attracted much
attention in the field of solar cells due to their optoelectronic characteristics that enable high power
conversion efficiencies. Perovskite-based solar cells’ efficiency has increased dramatically from
3.8% to more than 20% in just a few years, making them a promising low-cost alternative for
photovoltaic applications. The deposition of perovskite into a mesoporous metal oxide is an
influential factor affecting solar cell performance. Full coverage and pore filling into the porous metal
oxide are important issues in the fabrication of highly-efficient mesoporous perovskite solar cells.
In this work, we carry out a structural and quantitative investigation of CH3NH3PbI3 pore filling
deposited via sequential two-step deposition into two different mesoporous metal oxides—TiO2
and Al2O3. We avoid using a hole conductor in the perovskite solar cells studied in this work to
eliminate undesirable end results. Filling oxide pores with perovskite was characterized by Energy
Dispersive X-ray Spectroscopy (EDS) in Transmission Electron Microscopy (TEM) on cross-sectional
focused ion beam (FIB) lamellae. Complete pore filling of CH3NH3PbI3 perovskite into the metal
oxide pores was observed down to X-depth, showing the presence of Pb and I inside the pores.
The observations reported in this work are particularly important for mesoporous Al2O3 perovskite
solar cells, as pore filling is essential for the operation of this solar cell structure. This work presents
structural and quantitative proof of complete pore filling into mesoporous perovskite-based solar
cells, substantiating their high power conversion efficiency.

structural_and_quantitative_investigation_of.png structural_and_quantitative_investigation_of.pdf
Daniel Amgar, Sigalit Aharon, and Etgar Lioz. 9/7/2016. “Inorganic and Hybrid Organo-Metal PerovskiteNanostructures: Synthesis, Properties, and Applications.” Advanced Functional Materials, 2016,26: 8576–8593.Abstract

Hybrid perovskite and all-inorganic perovskite have attracted much attention
in recent years owing to their successful use in the photovoltaic field.
Usually the perovskite is used in its bulk form, although recently, perovskites’
nanocrystalline form has received increased attention. Recent developments
in the evolving research field of nanomaterial-based perovskite are reviewed.
Both hybrid organic-inorganic and all-inorganic perovskite nanostructures are
discussed, as well as approaches to tune the optical properties by controlling
the size and shape of perovskite nanostructures. In addition, chemical modifications
can change the perovskite nanostructures’ band-gap, similar to their
bulk counterpart. Several applications, including light-emitting diodes, lasers,
and detectors, demonstrate the latent potential of perovskite nanostructures.

inorganic_and_hybrid_organo-metal_perovskite.pdf
Bat-El Cohen and Etgar Lioz. 9/2016. “Parameters that control and influence the organo-metalhalide perovskite crystallization and morphology.” Front. Optoelectron, 1, 2016,9: 44–52.Abstract

This review discusses various parameters that influence and control the organo-metal halide perovskite crystallization process. The effect of the perovskite morphology on the photovoltaic performance is a critical factor. Moreover, it has a dramatic effect on the stability of the perovskite, which has significant importance for later use of the organo-metal perovskite in assorted applications. In this review, we brought together several research investigations that describe the main parameters that significantly influence perovskite crystallization, for example, the annealing process, the precursor solvent, anti-solvent treatment, and additives to the iteite solutions.mechanisms. Control over morphology is a key parameter to understand this attractive material; morphology control will be an additional step throughout its commercialization process. The review is divided to four parts, presenting various parameters influencing perovskite crystallization and morphology. Section 2 discusses the effect of the annealing process; Section 3 describes the precursor solvent, presenting the possible solvents being used in the deposition process; Section 4 presents the anti-solvent treatment and its effect on the cell properties; and Section 5 discusses additives that can be added to the perovskite solution before deposition.

parameters_that_control_and_influence_the_organo-metal_halide_perovskite_crystallization_and_morphology.pdf
Yanqi Luo, Shany Gamliel, Sally Nijem, Sigalit Aharon, Martin Holt, Benjamin Stripe, Volker Rose, Mariana I. Bertoni, Etgar Lioz, and David P. Fenning. 8/30/2016. “Spatially Heterogeneous Chlorine Incorporation in Organic−Inorganic Perovskite Solar Cells.” Chemistry of Materials, 18, 2016,28: 6536–6543.Abstract

Spatial heterogeneities in the chemical makeup of thin film photovoltaic devices are pivotal in determining device efficiency. We report the in-plane spatial distribution and degree of chlorine incorporation in organic−inorganic lead halide perovskite absorbers by means of nondestructive synchrotronbased nanoprobe X-ray fluorescence. The presence of chlorine is positively identified in CH3NH3PbI3 films synthesized with Clcontaining precursors and as an impurity in some films synthesized with nominally Cl-free precursors. The impurity may be introduced from precursors or as contaminants during film synthesis. The films formed from Cl-containing precursors contain roughly an order of magnitude higher amount of chlorine, with Cl:I values greater than 0.02 found whether Cl is present in either the organic or the inorganic precursor for both one- and two-step fabrication processes. A spatial variation in the Cl incorporation is observed within single particles and as well as between particles within a given film, and the standard deviation of the Cl:I ratio across the films is up to 30% of the average
value. Understanding and controlling the heterogeneous distribution of chlorine in hybrid perovskite layers may offer a path to improve their photovoltaic performance.

spatially_heterogeneous_chlorine_incorporation_in_organic.pdf spatially_heterogeneous_chlorine_incorporation_in_organic.png
Ravi K. Misra, Sigalit Aharon, Michael Layani, Shlomo Magdassi, and Etgar Lioz. 8/20/2016. “A mesoporous–planar hybrid architecture ofmethylammonium lead iodide perovskite basedsolar cells.” J. Mater. Chem. A, 2016,4: 14423-14429.Abstract

We report a hybrid mesoporous–planar architecture of methylammonium lead iodide perovskite based solar cells, to combine the benefits of both the mesoporous and planar architectures in a single device. A mesoporous-TiO2 grid was fabricated on a compact TiO2 layer, through a self-assembly process based on directional wetting, providing regions with and without mesoporous-TiO2, followed by perovskite deposition and back contact evaporation (hybrid cells). The hybrid cells showed up to 10.7% power conversion efficiency (PCE) as compared to 13.5% and 6.3% for their mesoporous and planar counterparts, respectively. Interestingly, the hybrid cells are found to show a short circuit current density
(Jsc) as high as the Jsc of the mesoporous TiO2 based cells and proved to conserve the current density even in the absence of mesoporous-TiO2 from planar parts of the hybrid cells. The cells showed the best fill factor as compared to their mesoporous and planar counterparts. The areal variation in the meso to planar ratio has also been realized by changing the grid size to demonstrate the effect of the architecture on the cell performance. Charge extraction measurements have been used to obtain insight into the recombination inside different solar cells architectures. The hybrid cell structure emerged as a novel promising design for perovskite solar cells.

a_mesoporous-planar_hybrid_architecture_of_methylammonium.png a_mesoporous-planar_hybrid_architecture_of.pdf
Ravi K. Misra, Laura Ciammaruchi, Sigalit Aharon, Dmitry Mogilyansky, Etgar Lioz, Iris Visoly-Fisher, and Eugene A. Katz. 7/2016. “Effect of Halide Composition on the PhotochemicalStability of Perovskite Photovoltaic Materials.” ChemSusChem, 2016, 9: 1 – 7. effect_of_halide_composition_on_the_photochemical.png effect_of_halide_composition_on_the_photochemical_stability.pdf
Sigalit Aharon and Etgar Lioz. 4/2016. “Two Dimensional Organometal Halide Perovskite Nanorods withTunable Optical Properties.” Nano Lett., 5, 2016,16: 3230–3235.Abstract

Organo-metal halide perovskite is an efficient light harvester in photovoltaic solar cells. Organometal halide perovskite is used mainly in its “bulk” form in the solar cell. Confined perovskite nanostructures could be a promising candidate for efficient optoelectronic devices, taking advantage of the superior bulk properties of organo-metal halideperovskite, as well as the nanoscale properties. In this paper, we present facile low-temperature synthesis of two-dimensional (2D) lead halide perovskite nanorods (NRs). These NRs show a shift to higher energies in the absorbance and in the photoluminescence compared to the bulk material, which supports their 2D structure. X-ray diffraction (XRD) analysis of the NRs demonstrates their 2D nature combined with the tetragonal 3D perovskite structure. In addition, by alternating the halide composition, we were able to tune the optical properties of the NRs. Fast Fourier transform, and electron diffraction show the tetragonal structure of these NRs. By varying the ligands ratio (e.g., octylammonium to oleic acid) in the synthesis, we were able to provide the formation mechanism of these novel 2D perovskite NRs. The 2D perovskite NRs are promising candidates for a variety of optoelectronic applications, such as light-emitting diodes, lasing, solar cells, and sensors.

two_dimensional_organometal_halide_perovskite_nanorods_with.png two_dimensional_organo-metal_halide_perovskite_nanorods.pdf

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