Synthesis Of Undoped Hole Transport Materials And Their Application In Trans Perovskite Solar Cells

With the rapid improvement in photoelectric conversion efficiency of perovskite solar cells in recent years,it is expected to be developed into commercial products,especially in the auxiliary power supply for portable and wearable devices.Perovskite material is easy to decompose in wet environment and continuous light condition,which is the main reason that it cannot be commercialized on a large scale.The structure of perovskite solar cells is mainly derived from the mesoporous structure of dye-sensitized solar cells and the planar structure of organic solar cells,which is a typical multi-layer film device structure.The interface characteristics between the electron transport layer,the hole transport layer and the electrode of perovskite solar cell have a great influence on the efficiency and stability of the perovskite solar cell.Surveying from the interface materials,new materials for the electron transport layer and hole transport layer can promote the interface charge extraction,passivation of perovskite grain boundary defects,block ion migration and reduce water oxygen penetration,so as to inhibit the decomposition of perovskite materials,improve the efficiency and stability of perovskite solar cells.At present,trans-perovskite solar cells can be processed by solution method,which simplifies the preparation process and reduces the production cost.And it provides a basis for mass production of the products.In this paper,a series of tetrathiafulvalene derivatives were designed and synthesized to research the effects of different end groups on their photoelectric properties and device efficiency.The main research contents of this paper are as follows:（1）On the basis of density functional theory,B3LYP/6-31G（d）method was used to quantitatively calculate the designed molecules.With the help of Gaussian 09,the theoretical HOMO energy levels were obtained.The target molecules in the range of-4.8 e V to-5.40 e V were selected for synthesis.Theoretical calculation shows that the length of alkyl chain has no great effect on the HOMO level of molecule.When the end group is benzoic acid and pyridine,the HOMO level of pair molecule would change greatly.（2）By adjusting the length of alkyl chain in tetrathiafulvalene derivatives,the molecules were applied to trans-perovskite solar cells.It was found that compound ZL-2 and ZL-3 had erosion phenomenon and could not form film.In the molecules that are made into devices,ZL-1 has the highest device efficiency of 18.59%.ZL-4 has the highest device efficiency of19.53%.（3）Tetrathiafulvalene derivatives with different number of benzoic acid end groups were designed to regulate theoretical energy levels.In the quantitative calculation,the HOMO energy levels of ZL-5,ZL-6 and ZL-7 have a certain rule,showing a downward trend with the increase of benzoic acid groups.（4）From the perspective of device passivation,the introduction of pyrazine and pyridine group,can make the target compounds has certain passivation effect on perovskite layer.