Optical Model and Optimization for Coherent-Incoherent Hybrid Organic Solar Cells with Nanostructures

Embedding nanostructures in organic solar cells (OSCs) is a well-known method to improve the absorption efficiency of the device by introducing the plasma resonance and scattering effects without increasing the active layer thickness. The introduction of nanostructures imposes greater demands on the optical analysis method for OSCs. In this paper, the generalized rigorous coupled-wave analysis (GRCWA) is presented to analyze and optimize the performance of coherent-incoherent hybrid organic solar cells (OSCs) with nanostructures. Considering the multiple reflections of light scattered within the glass substrate by the device, the correction vector g is derived, then the modified expressions for the field and absorption distribution in OSCs are provided. The proposed method is validated by comparing the simulated results of various structures with results obtained by the generalized transfer matrix method (GTMM) and the “equispaced thickness method” (ETM). The results demonstrate that the proposed method can reduce the number of simulations by at least half compared to the ETM while maintaining accuracy. With the proposed method, we discussed the device performance depending on the geometrical parameters of nanostructures, and the optimization and analysis are accomplished for single and tandem OSCs. After optimization based on the proposed method, the performance of OSCs are significantly improved, which further demonstrates the practicality of the method.

Genuine nonlinearity and its connection to the modified Korteweg–de Vries equation in phase dynamics

The study of hyperbolic waves involves various notions which help characterise how these structures evolve. One important facet is the notion of genuine nonlinearity, namely the ability for shocks and rarefactions to form instead of contact discontinuities. In the context of the Whitham modulation equations, this paper demonstrate that a loss of genuine nonlinearity leads to the appearance of a dispersive set of dynamics in the form of the modified Korteweg de-Vries equation governing the evolution of the waves instead. Its form is universal in the sense that its coefficients can be written entirely using linear properties of the underlying waves such as the conservation laws and linear dispersion relation. This insight is applied to two systems of physical interest, one an optical model and the other a stratified hydrodynamics experiment, to demonstrate how it can be used to provide insight into how waves in these systems evolve when genuine nonlinearity is lost.

Role of inelastic couplings in the 4He + 208Pb elastic scattering in a wide energy range

The phenomenological strengths of the real part of the optical potential, obtained from elastic scattering data analyses within the optical model approach, present significant energy-dependence. This behavior has been associated to the intrinsic energy-dependence of the effective nucleon-nucleon interaction. However, in earlier works, we proposed that at least part of this dependence can arise from the effect of couplings to inelastic states of the nuclei. In order to deepen this study, in this paper we present extensive data analyses for the elastic scattering and inelastic excitation of 111 states of 208Pb, for the 4He + 208Pb system in a wide energy range. With the purpose of comparison, the theoretical cross sections are obtained in different approaches for the imaginary part of the potential, and within both contexts: optical model (distorted wave Born approximation) and coupled-channel calculations.