Search

Abstract We introduce a Tseng extragradient method for solving monotone inclusion problem in Banach space. A strong convergence result of an Halpern inertial extrapolation method for solving the resolvent of sum of two monotone operators without the knowledge of the Lipschitz constant was established. Lastly, we illustrate some numerical behavior of our iterative scheme to showcase the performance of the proposed method compared to other related results in the literature.

Abstract In this paper, we study the existence of solution of the generalized equilibrium problem (GEP) in the framework of an Hadamard manifold. Using the KKM lemma, we prove the existence of solution of the GEP and give the properties of the resolvent function associated with the problem under consideration. Furthermore, we introduce an iterative algorithm for approximating a common solution of the GEP and a fixed point problem. Using the proposed method, we obtain and prove a strong convergence theorem for approximating a solution of the GEP, which is also a fixed point of a nonexpansive mapping under some mild conditions. We give an application of our convergence result to a solution of the convex minimization problem. To illustrate the convergence of the method, we report some numerical experiments. The result in this paper extends the study of the GEP from the linear settings to the Hadamard manifolds.

This paper presents the results of a combined experimental and computational study of the mechanisms of blister formation, and their effects on the degradation of organic light emitting devices (OLEDs). Blister formation is attributed to the effects of thermally induced mismatch stresses associated with applied bias. These result in interfacial cracking phenomena that are affected by the solvents that are used in OLED fabrication. The OLEDs are first fabricated using an electron transport layer of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) deposited on an active layer made from solutions of poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] dissolved in different solvents (toluene, chloroform, and chlorobenzene). The formation of blisters and degradation is then studied under applied bias for devices fabricated using different solvents (toluene, chloroform, and chlorobenzene) and emissive layer thicknesses. The underlying layer mechanical properties are then incorporated into interfacial fracture mechanic models that explain the formation of blisters that degrade the performance of OLED structures.

This paper uses a combination of experiments and theory to study the effects of annealing temperature on the mechanical properties of hybrid organic–inorganic perovskites (HOIPs). We examined the mechanical (hardness and Young’s modulus), microstructural, and surface topography properties of the HOIP film at different annealing temperatures ranging from 80 to 170 °C. A mechanism-based strain gradient (MSG) theory is used to explain indentation size effects in films at different annealing temperatures. Intrinsic film yield strengths and hardness values (deduced from the MSG theory) are then shown to exhibit a Hall–Petch dependence on the inverse square root of the average grain size. The implications of the results are then discussed for the design of mechanically robust perovskite solar cells.

Annealing is one of the processing methods that are used for the fabrication of defect-free, photoactive perovskite films with compact grains in highly efficient and stable perovskite solar cells (PSCs). Thus, the annealing temperature is a key parameter for the control of the interdiffusion (of constituent elements) in photoactive films. In this paper, we present the results of a systematic study of the effects of annealing on the interdiffusion of constituent elements in efficient formamidinium-based PSCs. We also explore the effects of annealing-induced interdiffusion on layer microstructures, local strains, and the optoelectronic properties of perovskite films. We observe a dramatic upward diffusion of tin (Sn) and titanium (Ti) from fluorine-doped tin oxide and titanium dioxide (TiO2) to the perovskite films. We also observe a downward diffusion of lead (Pb) and iodine (I) from the perovskite films to the mesoporous layer of the electron transporting layer (ETL), after annealing at temperatures between 100 and 150 °C. The diffused I substitutes for Ti in the ETL, which improves the optoelectronic properties of the films, for annealing temperatures between 100 and 130 °C. The annealing-induced interdiffusion that occurs at higher temperatures (between 140 and 150 °C) results in higher levels of interdiffusion, along with increased local strains that lead to the nucleation of pores and cracks. Finally, the implications of the results are discussed for the design of PSCs with improved photoconversion efficiencies and stability.

This paper presents the results of experimental and theoretical studies of the effects of pressure and thermal annealing on the photo-conversion efficiencies (PCEs) of polymer solar cells with active layers that consist of a mixture of poly(3-hexylthiophene-2,5-diyl) and fullerene derivative (6,6)-phenyl-C61-butyric acid methyl ester. The PCEs of the solar cells increased from ∼2.3% (for the unannealed devices) to ∼3.7% for devices annealed at ∼150 °C. A further increase in thermal annealing temperatures (beyond 150 °C) resulted in lower PCEs. Further improvements in the PCEs (from ∼3.7% to ∼5.4%) were observed with pressure application between 0 and 8 MPa. However, a decrease in PCEs was observed for pressure application beyond 8 MPa. The improved performance associated with thermal annealing is attributed to changes in the active layer microstructure and texture, which also enhance the optical absorption, mobility, and lifetime of the optically excited charge carriers. The beneficial effects of applied pressure are attributed to the decreased interfacial surface contacts that are associated with pressure application. The implications of the results are then discussed for the design and fabrication of organic solar cells with improved PCEs.

This paper presents the results of pressure-effects on performance characteristics of near-infra-red perovskite light emitting diodes (PeLEDs) using a combination of experimental and analytical/computational approaches. First, pressure-effects are studied using models that consider the deformation and contacts that occur around interfacial impurities and interlayer surface roughness in PeLEDs. The predictions from the model show that the sizes of the interfacial defects decrease with increasing applied pressure. The current–voltage characteristics of the fabricated devices are also presented. These show that the PeLEDs have reduced turn-on voltages (from 2.5 V to 1.5 V) with the application of pressure. The associated pressure-induced reductions in the defect density and the bandgaps of the perovskite layer are then used to explain the improved performance characteristics of the PeLED devices.

This paper explores the extent to which pre-buckling of layers (in thin film multilayered structures) can be used to increase the flexibility of organic electronic devices. The deformation of wavy/buckle profiles, with a range of nano- and micro-scale wavelengths, is modeled using finite element simulations. The predictions from the models are then validated using experiments that involve the bending of layered structures that are relevant to flexible organic electronics. The introduction of pre-buckled profiles is shown to increase the range of deformation that is applied to model structures, prior to onset of significant stresses and strains. The implications of the work are discussed for the design of robust flexible organic solar cells.

This paper presents the results of an analytical and computational study of the contacts and interfacial fracture associated with the cold welding of Organic Light Emitting diodes (OLEDs). The effects of impurities (within the possible interfaces) are explored for contacts and interfacial fracture between layers that are relevant to model OLEDs. The models are used to study the effects of adhesion, pressure, thin film layer thickness and dust particle modulus (between the contacting surfaces) on contact profiles around impurities between cold-welded thin films. The lift-off stage of thin films (during cold welding) is then modeled as an interfacial fracture process. A combination of adhesion and interfacial fracture theories is used to provide new insights for the design of improved contact and interfacial separation during cold welding. The implications of the results are discussed for the design and fabrication of cold welded OLED structures.