Osman M. Bakr

King Abdullah University of Science and Technology

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Omar F. Mohammed

King Abdullah University of Science and Technology

Jun Yin

Hong Kong Polytechnic University

Bekir Türedi

King Abdullah University of Science and Technology

Xiaopeng Zheng

National Renewable Energy Laboratory

Makhsud I. Saidaminov

University of Victoria

Ayan A. Zhumekenov

King Abdullah University of Science and Technology

Luis Gutiérrez‐Arzaluz

King Abdullah University of Science and Technology

Husam N. Alshareef

King Abdullah University of Science and Technology

İD

İbrahim Dursun

Cornell University

Issam Gereige

Saudi Aramco (United States)

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King Abdullah University of Science and Technology

173

Chinese Academy of Sciences

University of Toronto

Soochow University

University of Chinese Academy of Sciences

Kootenay Association for Science & Technology

University of California, Berkeley

Lawrence Berkeley National Laboratory

University of Cambridge

Peking University

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Energy & Environmental Science (2024)

Martin J. Hillenbrand Christoph Helbig Roland Marschall Xin Zhao Zhiqiang Fu

10.1039/d4ee90026j

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Citations (0)

Halide Perovskites: Metal Halide Perovskites for Solar‐to‐Chemical Fuel Conversion (Adv. Energy Mater. 13/2020)

Advanced Energy Materials (2020)

Jie Chen Chunwei Dong Hicham Idriss Omar F. Mohammed Osman M. Bakr

In article number 1902433, Osman M. Bakr and co-workers review the advancements made in the development of halide perovskites in photocatalyst particle-suspension systems, photoelectrode thin-film systems, and photovoltaic-(photo)electrocatalysis systems towards solar-to-chemical fuel conversion. Strategies for yielding stable and efficient halide perovskites are discussed, alongside an analysis of the design of device configurations for water splitting, hydrogen iodide splitting, and CO2 reduction.

Hydrogen halide

Hydrogen iodide

10.1002/aenm.202070059

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Citations (17)

The Surface of Hybrid Perovskite Crystals: A Boon or Bane

ACS Energy Letters (2017)

Banavoth Murali Emre Yengel Chen Yang Wei Peng Erkki Alarousu

Hybrid perovskite single crystals have garnered tremendous research attention and are expected to be next-generation materials for high-efficiency photoactive devices. Therefore, it is fundamentally important to understand the relationship between the optoelectronic properties of these materials and the marginally exploited surface chemistry in ambient air. For instance, a strong surface disorder, including hydration and ion migration, can possibly lead to extremely different optical and electronic properties at the surface compared to the bulk of the single crystal (SC). From this perspective, we evaluate the key variables that underlie the perovskite SC surface restructuring in ambient air and discuss their merits and limitations. In addition, a comprehensive picture of surface disordering, the remarkable change in the charge carrier dynamics and carrier mobility, surface hydration, and the effect of ion migration on the surface behavior will be discussed. Finally, surface passivation methods are highlighted to resolve or overcome the challenges for device integration.

Passivation

Charge carrier

Carrier lifetime

Surface charge

10.1021/acsenergylett.6b00680

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Citations (103)

A Simple n-Dopant Derived from Diquat Boosts the Efficiency of Organic Solar Cells to 18.3%

ACS Energy Letters (2020)

Yuanbao Lin Mohamad Insan Nugraha Yuliar Firdaus Alberto D. Scaccabarozzi Filip Aniés

Molecular doping has recently been shown to improve the operating characteristics of organic photovoltaics (OPVs). Here, we prepare neutral Diquat (DQ) and use it as n-dopant to improve the performance of state-of-the-art OPVs. Adding DQ in ternary bulk-heterojunction (BHJ) cells based of PM6:Y6:PC71BM is found to consistently increase their power conversion efficiency (PCE) from 16.7 to 17.4%. Analyses of materials and devices reveal that DQ acts as n-type dopant and morphology modifier for the BHJ leading to observable changes in its surface topography. The resulting n-doped BHJs exhibit higher optical absorption coefficients, balanced ambipolar transport, longer carrier lifetimes and suppressed bimolecular recombination, which are ultimately responsible for the increased PCE. The use of DQ was successfully extended to OPVs based on PM6:BTP-eC9:PC71BM for which a maximum PCE of 18.3% (uncertified) was achieved. Our study highlights DQ as a promising dopant for application in next generation organic solar cells.

Ambipolar diffusion

10.1021/acsenergylett.0c01949

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Citations (271)

Color-pure red light-emitting diodes based on two-dimensional lead-free perovskites

Science Advances (2020)

Fanglong Yuan Xiaopeng Zheng Andrew Johnston Ya‐Kun Wang Chun Zhou

It remains a central challenge to the information display community to develop red light-emitting diodes (LEDs) that meet demanding color coordinate requirements for wide color gamut displays. Here, we report high-efficiency, lead-free (PEA)2SnI4 perovskite LEDs (PeLEDs) with color coordinates (0.708, 0.292) that fulfill the Rec. 2100 specification for red emitters. Using valeric acid (VA)-which we show to be strongly coordinated to Sn2+-we slow the crystallization rate of the perovskite, improving the film morphology. The incorporation of VA also protects tin from undesired oxidation during the film-forming process. The improved films and the reduced Sn4+ content enable PeLEDs with an external quantum efficiency of 5% and an operating half-life exceeding 15 hours at an initial brightness of 20 cd/m2 This work illustrates the potential of Cd- and Pb-free PeLEDs for display technology.

Lead (geology)

10.1126/sciadv.abb0253

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Citations (184)

Transparent Organic and Metal Halide Tandem Scintillators for High-Resolution Dual-Energy X-ray Imaging

ACS Energy Letters (2023)

Wenyi Shao Tengyue He Jianxin Wang Yang Zhou Peng Yuan

Dual-energy X-ray imaging (DEXI) is a cutting-edge technology that provides more detailed material-specific information than the traditional single-energy X-ray imaging strategy. Herein, we designed and fabricated a top-filter-bottom (TFB) sandwich structure scintillator for high-resolution DEXI within a single exposure. More specifically, the low- and high-energy X-ray photons were sequentially absorbed by the top and bottom scintillators and were efficiently converted into their corresponding emission colors. By discriminating between these different emission spectra of the transparent TFB sandwich structure scintillator, DEXI can provide not only unique X-ray energy information but also an exceptional resolution of approximately 18 lp/mm on stacked images that surpasses most of the reported single-layer organic- and metal halide-based scintillators. The conceptual demonstrations of decomposition and reconstruction in DEXI were also realized on several biological imaging objects. This breakthrough research paves the way for the development of scintillator architectures specifically designed for DEXI.

Tandem

10.1021/acsenergylett.3c00784

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Citations (25)

Determination of nanoparticle size distribution together with density or molecular weight by 2D analytical ultracentrifugation

Nature Communications (2011)

Randy P. Carney Jin Young Kim Huifeng Qian Rongchao Jin Hakim Mehenni

Nanoparticles are finding many research and industrial applications, yet their characterization remains a challenge. Their cores are often polydisperse and coated by a stabilizing shell that varies in size and composition. No single technique can characterize both the size distribution and the nature of the shell. Advances in analytical ultracentrifugation allow for the extraction of the sedimentation (s) and diffusion coefficients (D). Here we report an approach to transform the s and D distributions of nanoparticles in solution into precise molecular weight (M), density (ρP) and particle diameter (dp) distributions. M for mixtures of discrete nanocrystals is found within 4% of the known quantities. The accuracy and the density information we achieve on nanoparticles are unparalleled. A single experimental run is sufficient for full nanoparticle characterization, without the need for standards or other auxiliary measurements. We believe that our method is of general applicability and we discuss its limitations. Nanoparticles continue to find research and industrial applications, but no single technique exists to characterise their physical properties. Now, an analytical ultracentrifugation method is described which allows the simulataneous determination of nanoparticle size, density and molecular weight distribution.

Analytical Ultracentrifugation

Characterization

Sedimentation

Particle (ecology)

10.1038/ncomms1338

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Citations (223)

Electrolyte Failure and Reconstruction towards Li–S Batteries Operating from –20 °C to 100 °C

Energy & Environmental Science (2024)

Dong Guo Simil Thomas Jehad K. El‐Demellawi Zixiong Shi Zhiming Zhao

Lithium-sulfur (Li-S) batteries are deemed one of the most promising high-energy battery technologies. However, their operation under thermal extremes, e.g., subzero and above 60 °C, remains largely underexplored. Especially, high...

10.1039/d4ee03191a

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Citations (1)

Metal Halide Perovskite and Phosphorus Doped g-C₃N₄ Bulk Heterojunctions for Air-Stable Photodetectors

ACS Energy Letters (2019)

Zhixiong Liu Yunpei Zhu Jehad K. El‐Demellawi Dhinesh Babu Velusamy Ahmed M. El‐Zohry

In this work, we fabricate photodetectors made of methylammonium lead trihalide perovskite (MLHP) and phosphorus-doped graphitic carbon nitride nanosheets (PCN-S). Using thermal polymerization, PCN-S with a reduced band gap, are synthesized from low-cost precursors, making it feasible to form type-II bulk heterojunctions with perovskites. Owing to the bulk heterojunctions between PCN-S and MLHP, the dark current of the photodetectors significantly decreases from ∼10–9 A for perovskite-only devices to ∼10–11 A for heterojunction devices. As a result, not only does the on/off ratio of the hybrid devices increase from 103 to 105 but also the photodetectivity is enhanced by more than 1 order of magnitude (up to 1013 Jones) and the responsivity reaches a value of 14 A W–1. Moreover, the hybridization of MLHP with PCN-S significantly modifies the hydrophilicity and morphology of the perovskite films, which dramatically increases their stability under ambient conditions. The hybrid photodetectors, described here, present a promising new direction toward stable and efficient optoelectronic applications.

Trihalide

Thermal Stability

10.1021/acsenergylett.9b01339

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Citations (48)

Modulation of Broadband Emissions in Two-Dimensional ⟨100⟩-Oriented Ruddlesden–Popper Hybrid Perovskites

ACS Energy Letters (2020)

Jun Yin Rounak Naphade Luis Gutiérrez‐Arzaluz Jean‐Luc Brédas Osman M. Bakr

Two-dimensional (2D) Ruddlesden–Popper (RP) perovskites are emerging materials for light-emitting applications. Unfortunately, their desirable narrowband emission coexists with broadband emissions, which limits the color quality and performance of the light source. However, the origin of such broadband emission in ⟨100⟩-oriented perovskites is still under debate. Here, we experimentally and theoretically demonstrate that unlike ⟨110⟩-oriented RP perovskites, the broadband emission of the 2D ⟨100⟩-oriented RP (PEA)2PbI4 (PEA = C6H5C2H4NH3+) perovskites originates from defect-related luminescence centers. We find that the broadband emission of this prototype 2D structure can be largely suppressed by using excess PEAI treatment. Density functional theory (DFT) calculations indicate that iodine (I) vacancies both in the bulk and on the surface are responsible for the broadband emission. We attribute the decreased broadband emission after PEAI treatment to the passivation of both undercoordinated Pb2+ ions on the surface and I vacancies in the bulk through I– ion migration.

Narrowband

Passivation

Modulation (music)

10.1021/acsenergylett.0c01047

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Citations (98)