Abstract A series of D-A-π-A organic dyes are taken into consideration to study the influence of different internal acceptor groups and thiophene based π-spacers on their efficiency in dye-sensitized solar cells (DSSCs). Density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods are used for investigating the electronic excitations along with their geometrical and charge transport properties. HOMO, LUMO energy levels and HOMO-LUMO energy gap helped in the understanding of energy levels appropriate for electron injection, electron transfer and dye regeneration. Thereafter, the calculations for short circuit current density (JSC) were performed by considering injection driving force (ΔGinj), dye regeneration energy (ΔGreg) and light-harvesting efficiency (LHE). In addition to this, charge transport properties like electron reorganization energy (λe), hole reorganization energy (λh), electron affinity (EA) and ionization potential (IP) are also reported. The results show that the insertion of internal acceptor in D-π-A system and variation in the length of π-spacer results in red-shifted absorption along with improved photovoltaic properties. Hence, the main purpose of this present study is to provide a theoretical background for proper designing and structural modifications in the development of efficient dyes in dye-sensitized solar cells (DSSCs).

中文翻译：

---

DA-π-A 系统中内部受体和基于噻吩的 π-间隔基对高效 DSSC 的光物理和电荷传输特性的影响：DFT 见解

摘要 考虑了一系列DA-π-A有机染料，研究了不同内部受体基团和噻吩基π-间隔基对其在染料敏化太阳能电池（DSSCs）中的效率的影响。密度泛函理论 (DFT) 和瞬态密度泛函理论 (TDDFT) 方法用于研究电子激发及其几何和电荷传输特性。HOMO、LUMO 能级和 HOMO-LUMO 能隙有助于了解适合电子注入、电子转移和染料再生的能级。此后，通过考虑注入驱动力（ΔGinj）、染料再生能量（ΔGreg）和光捕获效率（LHE）来计算短路电流密度（JSC）。除此之外，还报告了电荷传输特性，如电子重组能 (λe)、空穴重组能 (λh)、电子亲和力 (EA) 和电离势 (IP)。结果表明，D-π-A 系统中内部受体的插入和 π-间隔物长度的变化导致红移吸收以及改善的光伏性能。因此，本研究的主要目的是为在染料敏化太阳能电池 (DSSC) 中开发有效染料的正确设计和结构修改提供理论背景。结果表明，D-π-A 系统中内部受体的插入和 π-间隔物长度的变化导致红移吸收以及改善的光伏性能。因此，本研究的主要目的是为在染料敏化太阳能电池 (DSSC) 中开发有效染料的正确设计和结构修改提供理论背景。结果表明，D-π-A 系统中内部受体的插入和 π-间隔物长度的变化导致红移吸收以及改善的光伏性能。因此，本研究的主要目的是为在染料敏化太阳能电池 (DSSC) 中开发有效染料的正确设计和结构修改提供理论背景。