Disigning and simulation of organic molecules and materials for applications in solar energy harvesting and nonlinear optics

Abstract

Proposed research works emphasized towards designing and simulation of the organic-based molecules and materials for use in solar energy harvesting and nonlinear optics that have growing phase for sustainable energy solutions and cutting-edge optical technology. Organic materials as compared to inorganic ones, received a lot of interest by scientific community due to their unique structural multiformity and electrical characteristics. The proposed thesis mainly deals with strategies for designing and simulation of such materials to enhance their photovoltaic performance and nonlinear optical response. newlineTo see the electronic properties specifically, their lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) levels is crucial in the designing of effective organic compounds for organic photovoltaic s (OPVs). Nonlinear optical (NLO) materials have verity of applications such as optical switching, frequency conversion, and telecommunications. The design of these materials focuses on enhancing hyperpolarizability, a key parameter dictating their NLO response. To improve photovoltaic performance and NLO response we have utilized push pull approach. Advanced computational simulations such as density functional theory (DFT) and time-dependent DFT (TD-DFT) theory have been utilized for optimizing the geometry of molecules and featuring these materials. Taking into consideration of proposed research work, the proposed thesis work have comprises of seven chapter. newlineChapter 1 has two parts: chapter 1A and chapter 1B which deals with the detail discussions of dye sensitized solar cells and nonlinear optics. Chapter 2 is common for both parts of the thesis. Chapter 1 and chapter 2 can be summarized as: newlineChapter 1: Chapter 1 comprises of two parts; chapter 1A and 1B and both section were provide a specific aspects of proposed research work. In Chapter 1A, a detailed introduction has been given about the dye sensitized solar cell. In order to describe the subject matter, a brief literature survey has been given and the main emphasis has been given to the theoretical finding in literature. In Chapter 1B, the detail discussion and basic principle of linear and nonlinear optics have been given. Further, a brief literature review, and objective of proposed research work have also been discussed. newline2 newlineChapter 2: Chapter 2 describe a detailed description of different methodology such as newlineHF, DFT and TD-DFT etc. which were employed in proposed research investigation. newlineChapter 2 was common for both part of the thesis. newlineChapter 3 In this chapter, we have explores the critical role of and#960;-bridge engineering in newlineenhancing the performance of metal-free dye-sensitized solar cells (DSSCs) and their newlineoptoelectronic properties. In the present quantum chemical investigation we have newlinefocused on boron embedded and#960;-spacers and strategically designed dyes (1-9) by newlineconsidering thiophene fused borepins also known as a dithienoborepin (DTB) and#960;-linker newlineas a prototype. newline1 2 3 4 5 newline6 7 8 9 newlineFigure 1. Designed molecular structure of dye sensitizer 1-9 newlineThe designed molecular frameworks were presented in Figure 1. Appropriate and#960;- newlinelinker helps to improve the light harvesting efficiency and to reduce the energy gap newlinedifference between HOMO and LUMO. Further to improve the photovoltaic newlineperformance and to check the efficiency of and#960;-bridge we have replaced the donor newline3 newlinetriphenyl amine moieties with various donor groups. newlineThe density functional theory implemented with Gaussian 16 program was exploited for ground state (S0) geometry optimization. Geometry optimization calculations have been done with no restriction of symmetry using the B3LYP newline