A5003747905- Perovskite Materials and Applications
- Conducting polymers and applications
- Quantum Dots Synthesis And Properties
- Organic Electronics and Photovoltaics
- Chalcogenide Semiconductor Thin Films
- Organic Light-Emitting Diodes Research
- Solid-state spectroscopy and crystallography
- ZnO doping and properties
- Thin-Film Transistor Technologies
- Optical properties and cooling technologies in crystalline materials
- Advanced Memory and Neural Computing
- TiO2 Photocatalysis and Solar Cells
- Molecular Junctions and Nanostructures
- Electronic and Structural Properties of Oxides
- Luminescence and Fluorescent Materials
- Analytical Chemistry and Sensors
- 2D Materials and Applications
- Advanced Photocatalysis Techniques
- Copper-based nanomaterials and applications
- Transition Metal Oxide Nanomaterials
- Gas Sensing Nanomaterials and Sensors
- Crystallization and Solubility Studies
- Solid State Laser Technologies
- Supercapacitor Materials and Fabrication
- Lanthanide and Transition Metal Complexes
Indian Institute of Science Bangalore
2020-2025
King Saud University
2025
University of Cambridge
2013-2022
University of Oxford
2018-2022
Cavendish Hospital
2014-2019
Brighter perovskite LEDs Organic-inorganic hybrid perovskites such as methyl ammonium lead halides are attractive low-cost light-emitting diode (LED) emitters. This is because, unlike many inorganic nanomaterials, they have very high color purity. Cho et al. made two modifications to address the main drawback of these materials, their low luminescent efficiency. They created nanograin materials lacking free metallic lead, which helped confine excitons and avoid quenching. The had a current...
Already exhibiting solar to electrical power conversion efficiencies of over 17%, organic–inorganic lead halide perovskite cells are one the most promising emerging contenders in drive provide a cheap and clean source energy. One concern however, is potential toxicology issue lead, key component archetypical material. The likely substitute tin, which like also group 14 metal. While tin perovskites have shown good semiconducting behaviour, instability its 2+ oxidation state has thus far...
The highest power conversion efficiencies (PCEs) reported for perovskite solar cells (PSCs) with inverted planar structures are still inferior to those of PSCs regular structures, mainly because lower open-circuit voltages (Voc). Here we report a strategy reduce nonradiative recombination the devices, based on simple solution-processed secondary growth technique. This approach produces wider bandgap top layer and more n-type film, which mitigates recombination, leading an increase in Voc by...
To date, there have been a plethora of reports on different means to fabricate organic-inorganic metal halide perovskite thin films; however, the inorganic starting materials limited halide-based anions. Here we study role anions in solution and their influence upon crystal growth, film formation device performance. We find that by using non-halide lead source (lead acetate) instead chloride or iodide, growth is much faster, which allows us obtain ultrasmooth almost pinhole-free films simple...
Solution-processed metal halide perovskite semiconductors, such as CH3NH3PbI3, have exhibited remarkable performance in solar cells, despite having non-negligible density of defect states. A likely candidate is vacancies within the crystals, or presence metallic lead, both generated due to imbalanced I/Pb stoichiometry which could evolve during crystallization. Herein, we show that addition hypophosphorous acid (HPA) precursor solution can significantly improve film quality, electronically...
Organic–inorganic perovskites, such as CH3NH3PbX3 (X = I, Br, Cl), have emerged attractive absorber materials for the fabrication of low cost high efficiency solar cells. Over last 3 years, there has been an exceptional rise in power conversion efficiencies (PCEs), demonstrating outstanding potential these perovskite materials. However, most device architectures, including simplest thin-film planar structure, a current–voltage response displays “anomalous hysteresis”, whereby output cell...
Efficient quasi-2D-structure perovskite light-emitting diodes (4.90 cd A−1) are demonstrated by mixing a 3D-structured material (methyl ammonium lead bromide) and 2D-structured (phenylethyl bromide), which can be ascribed to better film uniformity, enhanced exciton confinement, reduced trap density. As service our authors readers, this journal provides supporting information supplied the authors. Such materials peer reviewed may re-organized for online delivery, but not copy-edited or...
Abstract Metal-halide perovskites are at the frontier of optoelectronic research due to solution processability and excellent semiconductor properties. Here we use transient absorption spectroscopy study hot-carrier distributions in CH 3 NH PbI quantify key parameters. Above bandgap, non-resonant excitation creates quasi-thermalized carrier within 100 fs. During cooling, a sub-bandgap signal arises ∼1.6 eV, which is explained by interplay bandgap renormalization distributions. At higher...
Solution-processable metal halide perovskites show immense promise for use in photovoltaics and other optoelectronic applications. The ability to tune their bandgap by alloying various anions (for example, CH3NH3Pb(I1–xBrx)3, 0 < x 1) is however hampered the reversible photoinduced formation of sub-bandgap emissive states. We find that ion segregation takes place via defects, resulting iodide-rich low-bandgap regions close illuminated surface film. This may be driven strong gradient carrier...
Solution-processed organo-lead halide perovskites are produced with sharp, color-pure electroluminescence that can be tuned from blue to green region of visible spectrum (425–570 nm). This was accomplished by controlling the composition CH3NH3Pb(BrxCl1–x)3 [0 ≤ x 1] perovskites. The bandgap and lattice parameters change monotonically composition. films possess remarkably sharp band edges a clean bandgap, single optically active phase. These chloride–bromide potentially used in optoelectronic...
In lead halide perovskite solar cells, there is at least one recycling event of electron-hole pair to photon open circuit under illumination. This can a significant reduction in the external photoluminescence yield from internal yield. Here we show that, for an 70%, measure yields as low 15% planar films, where light out-coupling inefficient, but observe values high 57% films on textured substrates that enhance out-coupling. We analyse detail how externally measured rate constants and...
Organometallic lead-halide perovskite-based solar cells now approach 18% efficiency. Introducing a mixture of bromide and iodide in the halide composition allows tuning optical bandgap. We prepare mixed bromide–iodide lead perovskite films CH3NH3Pb(I1–xBrx)3 (0 ≤ x 1) by spin-coating from solution obtain with monotonically varying bandgaps across full range. Photothermal deflection spectroscopy, photoluminescence, X-ray diffraction show that following suitable fabrication protocols these...
Fundamental understanding of the charge transport physics hybrid lead halide perovskite semiconductors is important for advancing their use in high-performance optoelectronics. We field-effect transistors (FETs) to probe mechanism thin films methylammonium iodide (MAPbI3). show that through optimization thin-film microstructure and source-drain contact modifications, it possible significantly minimize instability hysteresis FET characteristics demonstrate an electron mobility (μFET) 0.5...
Cesium lead bromide (CsPbBr3) was recently introduced as a potentially high performance thin-film halide perovskite (HaP) material for optoelectronics, including photovoltaics, significantly more stable than MAPbBr3 (MA = CH3NH3+). Because of the importance single crystals to study relevant properties per se, grown under conditions comparable those used preparing thin films, i.e., low-temperature solution-based growth, are needed. We show here two simple ways, antisolvent-vapor saturation or...
Colloidal metal–halide perovskite quantum dots (QDs) with a dimension less than the exciton Bohr diameter DB (quantum size regime) emerged as promising light emitters due to their spectrally narrow light, facile color tuning, and high photoluminescence efficiency (PLQE). However, size-sensitive emission wavelength purity low electroluminescence are still challenging aspects. Here, we demonstrate highly efficient light-emitting diodes (LEDs) based on colloidal nanocrystals (NCs) in > (regime...
Abstract State‐of‐the‐art light‐emitting diodes (LEDs) are made from high‐purity alloys of III–V semiconductors, but high fabrication cost has limited their widespread use for large area solid‐state lighting. Here, efficient and stable LEDs processed solution with tunable color enabled by using phase‐pure 2D Ruddlesden–Popper (RP) halide perovskites a formula (CH 3 2 ) NH n −1 Pb I +1 reported. By vertically oriented thin films that facilitate charge injection transport, electroluminescence...
Low-bandgap CH3 NH3 (Pbx Sn1-x )I3 (0 ≤ x 1) hybrid perovskites (e.g., ≈1.5-1.1 eV) demonstrating high surface coverage and superior optoelectronic properties are fabricated. State-of-the-art photovoltaic (PV) performance is reported with power conversion efficiencies approaching 10% in planar heterojunction architecture small (<450 meV) energy loss compared to the bandgap (>100 cm2 V-1 s-1 ) intrinsic carrier mobilities.
Self-assembled hybrid perovskite quantum wells have attracted attention due to their tunable emission properties, ease of fabrication and device integration. However, the dynamics excitons in these materials, especially how they couple phonons remains an open question. Here, we investigate two widely used namely butylammonium lead iodide $(CH_3(CH_2)3NH_3)2PbI_4$ hexylammonium $(CH_3(CH_2)5NH_3)2PbI_4$, both which exhibit broad photoluminescence tails at room temperature. We performed...
A low-bandgap polymer:fullerene blend that has significantly reduced energetic losses from photon absorption to VOC is described. The charge-transfer state and polymer singlet are of nearly equal energy, yet the short-circuit current still reaches 14 mA cm(-2).
The influence of monovalent cation halide additives on the optical, excitonic, and electrical properties CH 3 NH PbI perovskite is reported. Monovalent with similar ionic radii to Pb 2+ , including Cu + Na Ag have been added explore possibility doping. Significant reduction sub‐bandgap optical absorption lower energetic disorder along a shift in Fermi level presence these cations has observed. bulk hole mobility additive‐based perovskites as estimated using space charge limited current...