We report a comprehensive study of the chemistry perovskite optoelectronic device degradation and show that redox reactions are fundamental to process for CH3NH3PbI3, CsPbI3, CsPbBr3 perovskites with Ag, Al, Yb, or Cr contacts. Using in situ X-ray diffraction measurements, we CH3NH3PbI3 devices equipped Al electrodes; find Al0 rapidly reduces Pb2+ Pb0, converting first (CH3NH3)4PbI6·2H2O then CH3NH3I. In scanning electron microscopy measurements moisture enables continued reaction layers by...

One merit of organic–inorganic hybrid perovskites is their tunable bandgap by adjusting the halide stoichiometry, an aspect critical to application in tandem solar cells, wavelength-tunable light emitting diodes (LEDs), and lasers. However, phase separation mixed-halide caused or applied bias results undesirable recombination at iodide-rich domains, meaning open-circuit voltage (VOC) pinning cells infrared emission LEDs. Here, we report approach suppress redistribution self-assembled...

Hybrid organic-inorganic halide perovskite semiconductors are attractive candidates for optoelectronic applications, such as photovoltaics, light-emitting diodes, and lasers. Perovskite nanocrystals of particular interest, where electrons holes can be confined spatially, promoting radiative recombination. However, nanocrystalline films based on traditional colloidal nanocrystal synthesis strategies suffer from the use long insulating ligands, low concentration, significant aggregation during...

Abstract A major breakthrough in the field of organic photovoltaics (OPVs) was development donor/acceptor heterojunction that aids separating Coulombically bound excitons are generated upon photoabsorption. Additionally, charge transfer (CT) states result from exchange carriers across interface believed to play an important role generation. Though thin films often disordered, enhancements local structural order at have recently been shown greatly influence CT state energetics and generation...

Singlet fission is a spin-allowed process of exciton multiplication that has the potential to enhance efficiency photovoltaic devices. The majority studies date have emphasized understanding first step singlet fission, where correlated triplet pair produced. Here, we examine separation pairs. We conducted temperature-dependent transient absorption on 6,3-bis(tri isopropylsilylethynyl)pentacene (TIPS-Pn) films, exothermic. evaluated time constants show their temperature dependence...

A novel solid-state design is presented for an organic intermediate band solar cell with electrically integrated triplet–triplet annihilation upconversion.

Metal halide perovskite semiconductors with small exciton binding energy have been widely used in solar cells and achieved rapid progress terms of device performance. However, the strong excitonic nature two-dimensional (2D) perovskites n values remains underexploited (n represents number inorganic monolayer sheets sandwiched between bulky organic cation layers). In this work, we report experimental evidence donor/acceptor charge-transfer (CT) states formed at 2D metal perovskite/organic...

Recently, hybrid perovskites have gained attention as sensitizers for molecular triplet generation. Layered, two-dimensional (2D) are especially well-suited this purpose because the donor (inorganic framework) and acceptor (organic layer) self-assembled into adjacent sheets, so that with appropriate energetics, triplets can be driven across interface. Here we examine interlayer energy transfer in a series of mixed-halide Dion–Jacobson 2D containing divalent naphthalene cations. We find...

Here we review an emerging class of 2D layered metal-halide perovskites that exhibit important photophysical behavior involving inorganic exciton-to-molecular triplet energy flow. These novel systems have potential to impact several energy-related fields and processes, including optoelectronics, photon upconversion strategies, triplet-based photocatalysis. Early studies provided initial guidance revealed intriguing questions more recent developments, in terms both expanded diversified...

The ability to undergo spin-allowed exciton multiplication makes singlet fission materials promising for photovoltaic applications. Here, we examine the separation of correlated triplet pairs, 1 (T…T), in polycrystalline pentacene films via temperature-dependent transient absorption spectroscopy. Single wavelength analysis reveals a profound delay (T…T) dynamics. Moreover, dynamics exhibit temperature dependence, whereas other features show no discernable dependence. Previous literatures...

While it has recently been recognized that organic donor-acceptor charge transfer (CT) state energies can vary substantially under different interfacial morphologies, this behavior is under-appreciated in the context of singlet fission solar cells where a specific alignment between triplet material and CT interface necessary to function device. In work, we demonstrate energy prototypical pentacene-C60 system around 1 eV most systems, but over 300 meV depending on composition morphology...

Computations, based on the ensemble-averaged compressible Navier-Stokes equations closed by shear-stress transport (SST) turbulence model, were performed to investigate effects of leading-edge airfoil fillet and inlet-swirl angle flow heat transfer in a turbine-nozzle guide vane. Three configurations simulated: no (baseline), whose thickness fades airfoil, endwall. For both fillets, maximum height above endwall is positioned along stagnation zone/line under condition swirl. each...

The ability to controllably enhance or suppress the luminescence contributions from different species in layered two-dimensional (2D) hybrid perovskites is beneficial for developing color-tunable broadband emitters. In particular, 2D exhibiting interlayer sensitized triplet emission their organic cations, final molecular profiles are often influenced by intermolecular interactions between neighboring chromophores. Embedding these chromophores within an inert host cation emerging strategy...

Tensile properties of three steels named A, B, and C were investigated. The quasi-static experiments carried out by using WDW-100D computer control testing machine while the high strain-rate Split Hopkinson Bars (SHTB). stress-strain curves materials obtained, tensile strength, elongation, energy dissipated acquired. From experimental results, Jonson-Cook constitutive model was use to describe behaviours materials. results showed that steel B had highest strength lowest elongation than A B....

Endothermic singlet fission (SF), an exciton multiplication process that produces a pair of high-energy triplet excitons (T1T1), is appealing for photovoltaic or photoelectrochemical applications, as it allows the conversion entropy into electronic chemical energy. The mechanistic aspects this are not entirely known, and strategies improving yield triplets via endothermic SF have been developed. In work we provide experimental evidence in photoexcited dimers perylene, S1 initially...

Abstract Computations, based on the ensemble-averaged compressible Navier-Stokes equations closed by shear-stress transport (SST) model of turbulence, were performed to investigate effects inlet swirl angle three-dimensional flow and heat transfer in two contoured endwall configurations. Swirl angles investigated include three constant (0°, 15°, 30°) a linearly varying from +30° at one −30° other. For all angles, mass-flow rate through nozzle was fixed so that higher angle, is velocity...

We report the first observation of charge-transfer (CT) states at 2D metal halide perovskite/organic heterojunctions. The perovskite (BAI)2(MAI)n-1(PbI2)n with various n values are used to form heterojunctions organic molecules (BA represents n-butylammonium and MA methylammonium). Charge-transfer features found in external quantum efficiency (EQE) versus wavelength curves only for strong excitonic BA2PbI4 (n=1) case when forming a heterojunction...

While interlayer triplet energy transfer has been studied in Ruddlesden-Popper 2D perovskites containing monovalent naphthalene cations, the photophysical properties of their Dion-Jacobson analogue have not reported. Here we examine a series mixed-halide divalent cations. We find that sensitized phosphorescence these compounds is dominated by excimer emission, but when lead halide exciton tuned near resonance with naphthalene, emission from monomer competes formation. Interlayer further...