Theoretical description of a novel dye-sensitized solar cell

更好地理解有机/混合光电子器件中的工艺可以使新技术的利用成为可能。这种理解需要在理论化学和理论物理学的新方法的发展，允许在溶液中和表面上的原子细节的超分子系统的描述。按照原项目的计划，该延续项目将处理染料敏化太阳能电池的模型。该系统由沉积在氧化锡（IV）上的卟啉衍生物和富勒烯的分子聚集体组成。要研究的过程是激发能量转移，电子转移以及电子注入到半导体。该系统的第一个实验结果已经公布。对该系统的详细理论研究是为了回答最终可能导致构建更高效的染料敏化太阳能电池的开放性问题。为了在原子分辨率下模拟整个系统，将利用混合量子-经典方法。该方法的基础上减少系统的哈密顿相关的电子状态。相对于这些相关的电子状态的波函数展开。这允许数值解的时间依赖薛定谔方程。相应的哈密顿矩阵依赖于参数的核坐标，这是从经典的分子动力学模拟。关于结果质量的关键标准是有效Hamilton矩阵的精确参数化。在过去的三年里，我证明了色散（伦敦范德华）相互作用的处理对分子态的能量和分子聚集体的光谱有巨大的影响。计划将相应的方法应用于染料敏化太阳能电池的模型。此外，该方法有待改进，特别是，扩展到允许计算环境诱导的激子耦合屏蔽。激子耦合是激子哈密顿矩阵的非对角元素，对整体结果有很大影响。用于进一步开发该方法的相应模型系统将是二萘嵌苯衍生物PTCDI的晶体结构。光谱和传输过程是要建模。在卟啉衍生物/富勒烯聚集体的情况下，依赖于聚集体构型的注入效率将被理解和优化。因此，将以原子分辨率描述染料敏化太阳能电池的完整模型。

A better understanding of the processes in organic/hybrid optoelectronic devices may enable the utilization of novel technologies. This understanding requires the development of new methods in theoretical chemistry and theoretical physics that allow for the description of supramolecular systems in solution and on surfaces in atomic detail. As planned for the original project this continuation project is to treat the model of a dye sensitized solar cell. The system consists of a molecular aggregate built of porphyrin derivatives and fullerenes deposited on tin (IV) oxide. The processes that are to be investigated are excitation energy transfer, electron transfer as well as electron injection into the semiconductor. First experimental results on this system have been published. A detailed theoretical investigation of the system is to answer open questions that may finally result in the construction of more efficient dye sensitized solar cells. In order to model the whole system in atomic resolution a mixed quantum-classical methodology is to be utilized. The method bases on the reduction of the system Hamiltonian to the relevant electronic states. The wavefunction is expanded with respect to these relevant electronic states. This allows for the numerical solution of the time-dependent Schrödinger equation. The respective Hamiltonmatrix depends parametrically on the nuclear coordinates which are to be derived from classical molecular dynamics simulations. The crucial criterion regarding the quality of the results is the accurate parameterization of the effective Hamiltonmatrix. During the last three years I demonstrated that the treatment of dispersive (London van-der-Waals) interaction has a huge impact on the energies of molecular states and on optical spectra of molecular aggregates. It is planned to apply the respective method to the model of a dye sensitized solar cell. Additionally, the methodology is to be improved and, particulary, extended to allow for the calculation of environmentally induced screening of excitonic coupling. The excitonic couplings are the non-diagonal elements of the excitonic Hamiltonmatrix and have a huge impact on the overall results. The respective model system for the further development of this methodology will be crystalline structures of the perylene derivative PTCDI. Optical spectra and transfer processes are to be modeled. In the case of the porphyrin-derivate/fullerene aggregate the injection efficiency in dependence of the aggregate configuration are to be understood and optimized. Thereby, the complete model of a dye-sensitized solar cell will be described in atomic resolution.