The demand for an ultrabroad optical material with a bandgap tunable from zero to at least 1–2 eV has been one of the driving forces for exploring new 2D materials since the emergence of graphene, ...transition metal dichalcogenides, and black phosphorus. As an ultra‐broadband 2D material with energy bandgap ranging from 0 to 1.2 eV, PtSe2 shows much better air stability than its analogue, black phosphorous. In this work, the superior nonlinear optical performance and ultrafast dynamics of layered PtSe2, and signatures of the transition from semiconductor to semimetal are systematically studied. Combining with rate equations, first‐principles calculation, and electrical measurements, a comprehensive understanding about the evolution of nonlinear absorption and carrier dynamics with increasing layer thickness is provided, indicating its promising potential in nanophotonic devices such as infrared detectors, optical switches, and saturable absorbers.
The superior nonlinear optical performance and ultrafast dynamics of layered PtSe2, as well as signatures of the transition from semiconductor to semimetal are investigated. The evolution of nonlinear absorption and carrier dynamics with increasing layer thickness demonstrate the promising potential in nanophotonic devices of PtSe2, such as infrared detectors, optical switches, and saturable absorbers.
A lead-free, pure phase double perovskite Cs2AgBiBr6 thin film (TF) is fabricated on an ITO glass plate through a three-step sequential vacuum thermal evaporation method followed by annealing. X-ray ...diffraction (XRD) analysis of the synthesized material revealed a cubic phase with a lattice constant of α = 11.26 Å. The TF exhibits UV and visible absorption with a bandgap estimated at 2.31 eV (303 K) and a red shift of 0.04 eV (363 K). The optical absorption spectrum is simulated using the modified band anti-crossing (BAC) model, determining the Cs2AgBiBr6 TF's theoretical relative refractive index (r.i.) as 2.10 (303 K) and 1.90 (363 K). Furthermore, a photodetector based on Ag/Cs2AgBiBr6/ITO/glass architecture was fabricated, showcasing excellent stability and self-powered photodetection properties under continuous illumination across a wide temperature range of 303–373 K. The device demonstrates a fast temporal response (13/9 ms), a responsivity of ∼1.0 × 10−4 A/W, and a detectivity of ∼2.5 × 107 Jones. Light sensitivity measurements reveal that the device is twice as sensitive at 373 K compared to room temperature, with negligible (1%) degradation in light sensitivity after 60 days of storage under normal ambient conditions.
•Fabrication of Cs2AgBiBr6 thin film (TF) by sequential vapour deposition process.•A new theoretical approach using modified BAC model to determine refractive index of the material.•Temperature dependent stability of the Cs2AgBiBr6 TF under ambient conditions.•Analysis of temperature dependent optoelectronic response of the photodetector and its stability.•Proposal of lead free environmentally friendly perovskite-based photodetector.
In this paper, we report characterization and performance results of lead bromide perovskite luminescent solar concentrator. CH3NH3PbBr3 fluorophores are synthesized by sonication method and examined ...by their X-ray diffraction pattern and scanning electron microscopy. Synthesized perovskite shows excitonic absorption at 524 nm and PL emission peak located at 532 nm with a Stokes shift around 8 nm. Micron-sized fluorophores are dissolved in prepared solutions and uniformly embedded in PMMA host with 0.006–0.120%wt concentration. Then, Fabricated devices are cut into 50 × 30 × 5 mm cuboid shapes and placed in a mirror surrounded configuration with an attached photovoltaic cell. Fabricated device is put under standard AM1.5 illumination and the output spectrum from the concentrator is acquired. Re-absorption in the samples is also measured by variable optical path method, showing red-shifts up to 13 nm in the output spectrum. Spatially resolved photoluminescence maps and optical efficiencies are also presented for each sample. Plus, a Monte-Carlo ray tracing algorithm is developed to assist better understanding the experimental results. Stability of fabricated samples are evaluated under high intensity UV illumination, reporting efficiency reduction around 15% after 24 h. Finally, Comparing current-voltage characterization of the attached photovoltaic cell reveals optimized efficiency enhancement in the 0.04%wt sample above 65%.
•Luminescent solar concentrators employing lead bromide perovskites are fabricated.•Durable functionality of perovskite fluorophores in PMMA matrix is observed.•Re-absorption in the samples is measured by variable optical path method.•Monte-Carlo ray tracing algorithm is developed to assist the experimental results.•68% boost in the optical efficiency is measured for the 0.04%wt sample.
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•Ionic liquids (ILs) aided-device engineering champions is widely reviewed.•The role of ILs in the production of high-quality perovskite film is discussed.•ILs can potentially improve ...the long-term stability of perovskite solar cells.•ILs represents a significant step toward reliable perovskite PV technology.
The efficiency of perovskite solar cells (PSCs) is rapidly increasing, so that their long-term operational stability has become a major focus for commercialization and market adoption. The development of novel strategies and materials to improve the stability of small and large solar modules without compromising power conversion efficiency (PCE) is an ongoing challenge. Ionic liquids (ILs) are emerging as useful additives, solvents, and charge transport materials for the preparation of highly efficient perovskite films. Perovskite crystallizes slowly in ILs to form large and uniform grains, and PSCs fabricated with high-quality perovskite films are efficient and stable. Herein we review recently developed systemic device engineering, and we discuss the impact of ILs in the production of highly efficient and stable PSCs. This review is intended to serve as a guide to develop highly crystalline perovskite films with larger grains and more homogeneous morphologies, all of which contribute to enhancing the stability of PSC performance. Recent progress in the use of ILs as solvents and additives for PSCs is a significant step toward developing reliable perovskite photovoltaic devices. Finally, we discuss challenges and future research directions for the fabrication of efficient and stable PSCs.
Metal halide perovskites (MHPs) dominate the class of wet processed semiconductors due to high photoluminescence quantum yield, tunable emission over a wide wavelength range, high carrier mobilities, ...and high absorption coefficient. Owing to these remarkable properties, MHPs cover next‐generation applications such as solar cells, light emitting diodes, lasers, photocatalysts, etc. Beside these fascinating applications, MHPs attract increased attention as fluorescent sensors for various chemical analytes and environmental changes such as temperature, etc. Likewise, high‐energy radiation detection is also displayed by the MHPs, like in scintillators. Here, the latest advances in MHPs fluorescent sensors and high‐energy X‐ray, gamma‐ray, and beta detectors are reviewed. The basics including match‐mismatch of MHPs for fluorescent sensing and radiation detection applications are discussed. Moreover, the mechanistic understanding of fluorescent sensing and radiation detection by MHPs is also elaborated. The authors conclude with outlooks on future opportunities for MHP fluorescent sensors and high‐energy radiation detectors.
Metal halide perovskites fluoresce efficiently, with tunable emission over a wide wavelength range. Emission color and quantum yield depend on chemical analytes, the presence of free charges, and the environment. Metal halide perovskites are versatile materials for efficient and selective fluorescent sensing and radiation detection applications. Their present status, challenges, and future outlooks are discussed in this review.
The structure of experimentally designed solar cells was optimized in terms of the photoactive layer thickness for both organic bulk heterojunction and hybrid perovskite solar cells. The photoactive ...layer thickness had a totally different behavior on the performance of the organic and hybrid solar cells. Analysis of the optical parameters using transfer matrix modeling within the Maxwell-Garnett effective refractive index model shows that light absorbance and exciton generation rate in the photoactive layer can be used to optimize the thickness range of the photoactive layer. Complete agreement between experimental and simulated data for solar cells with photoactive materials that have very different natures proves the validity of the proposed modeling method. The proposed simple method which is not time-consuming to implement permits to obtain a preliminary assessment of the reasonable range of layer thickness that will be needed for designing experimental samples.
Organic photovoltaic cells commonly use an active layer with a polycrystalline bulk heterojunction. However, for simplifying the fabrication process, it may be worthwhile to use an amorphous active ...layer to lessen the burden on processing to achieve optimal performance. While polymers can adopt amorphous phases, molecular glasses, small molecules that can readily form glassy phases and do not crystallize over time, offer an appealing alternative, being monodisperse species. Our group has developed a series of reactive molecular glasses that can be covalently bonded to chromophores to form glass‐forming adducts, and this strategy has been used to synthesize glass‐forming donor and acceptor materials. Herein, the results of devices incorporating these materials in either partially or fully amorphous active layers are summarized. Additionally, these molecular glasses can be used as ternary components in crystalline systems to enhance efficiency without perturbing the morphology.
The active layer in organic photovoltaic cells is usually a bulk heterojunction constituted of a polycrystalline array of phase‐segregated donor and acceptor domains; it is based on the demixion of polymers. However, in order to make it more sustainable, it may also be possible to use naturally glass‐forming materials to yield semi‐crystalline bulk heterojunctions, or fully amorphous homogeneous blends.
The semiconductor/dielectric interface controls the performance of organic field‐effect transistors (OFETs). Herein, the influence of both the molecular weight and the polarity of the solvent of a ...poly(methyl methacrylate) (PMMA)‐based gate dielectric on the performance of pentacene OFETs is systematically investigated, by studying surface energy, surface roughness, morphology, leakage current, and capacitance of the dielectric. Various existing views on the role of the surface energy are considered while deriving a correlation. Larger pentacene grains are observed when the film is grown on high molecular weight‐PMMA films cast from high dipole moment‐solvent. The electrical properties of the corresponding OFETs show great improvement compared to those of OFETs fabricated with low molecular weight‐PMMA film as the gate dielectric, irrespective of the solvent. The authors attribute this enhanced performance to the increased surface energy of the polymeric dielectric which turns out to be a strong function of its molecular weight and the dipole moment of the solvent. Bias‐stress measurements on the OFETs confirm this correlation.
The performance of organic field‐effect transistors critically depends on gate dielectric–semiconductor interfaces. The important parameters are molecular weight of the dielectric and polarity of the solvents. These parameters control surface energy of the polymeric gate dielectric, which defines the morphology of the semiconductor.
Curcumin, a natural dye found in the
rhizome, commonly called turmeric, is used as a photosensitizer in acrylamide-based photopolymers for holographic data storage. We studied the absorbance of ...photopolymer films that show two absorption bands due to curcumin, acrylamide monomer (AA), and the crosslinking agent N,N'-methylenebisacrylamide (MBA). Analysis of the real-time diffraction efficiency of these films shows a maximum of 16% for the sample with the highest curcumin concentration. Moreover, increasing the curcumin load enhanced the refractive index contrast from 7.8 × 10
for the photopolymer with the lowest curcumin load to 1.1 × 10
for the photopolymer with the largest load. The sensitivity and diffraction efficiency of the recorded gratings also increased from 7.0 to 9.8 cm·J
and from 7.9 to 16% with the increase in curcumin load, respectively. Finally, the influence of NaOH on the photopolymerization of the AA-curcumin-based sample shows a diffraction efficiency increase with the NaOH content, revealing that the curcumin enol form is more efficient as a photosensitizer.
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