Dynamics Simulations On The Self-assembly Of Didodecanoylamides Of α,ω-alkylidenediamines As Low Molecular Mass Organogelators

As one of the most promising cells in the group of new generation photovoltaic solar cells, dye sensitized solar cells (DSCs) have always drawn wide attention in the research field. Over the past decade, scholars have attempted to optimize or improve the structure of the components of the cells or look for new materials so as to improve the efficiency of the cells. The quasi-solid-state electrolytes (QS-DSCs), which are made from gel systems by adding gelling agents into traditional liquid electrolytes, have become a new issue in current studies. It can not only maintain the high mobility of ions at maximum like the liquid electrolytes and own the long-term stability of solid-state electrolytes, but also solve the seal leakage problem. Low molecular mass organogelators (LMOGs) are the key components to prepare QS-DSCs. The diamine compound has aroused general concern as its simple molecular structure for self-assembly and low raw material cost. The structural difference of the derivatives lies in having different numbers of-CH2-between two amides group in chain with different types of R groups. The series of experiments recently performed by our lab found that the number of-CH2-had remarkable influence on the morphology of LMOG resulting in significantly different efficiency of solar cells. The interactions at the molecular level can not be intuitively observed using experimental means. In contrast, molecular dynamics (MD) simulation can explain the conformational changes and the assembly processes in the dynamical processes from the perspective of intermolecular interaction. Therefore, we investigated by MD simulations which contributes to providing theoretical direction for electing and designing LOMGs.In the current work, the MD simulations of N,N’-l,8-octanediylbis-dodecanamide and N,N’-1,9-nonanediylbis-dodecanamide, which are served as gelator A and B, are carried out since they have extremely similar structures, to explore:(1) the dynamic features and self-assembly modes; (2) the relation between different self-assembly modes and morphologies; (3) the influence of solvents on self-assembly process.Chapter 1 systematically summarizes the research status and backgrounds concerned to our work. Chapter 2 generally introduces the theory of MD.Chapter 3 to 5 are the main portion of our paper. In chapter 3, we constructed initial structure systems of gelator A and B respectively arranged in parallel. Long-time simulations of MD on the above systems were carried out. Systematical study about assembly modes of the molecules of the gelators and interaction forces between molecules was made. We compared the difference of self-assembly modes between the two gelators which owns extremely similar structure.In chpater 4, initial structure systems of gelator A and B respectively arranged in amorphous configurations were constructed. We analysed self-assembly modes and calculated interaction forces. Comparing this part with Chapter 3, we aimed to making sure of assembly complexity of the gelator in different initial structure systems.In chapter 5, initial structure system of gelator A parallelly arranged in the solvents was built. After a long-time MD simulation, we discussed the influence of solvents on assembly modes of gelators. Chapter 6 was mainly written for conclusion and expectation.Since current studies on selection of type gelator used to form specific electrolytes are still performed by trail-and-error method, this study is of significance when seeking to design and select new gelators made from small organic molecules so as to improve the electronic and photovoltaic performances of DSCs.