The generation and collection efficiency of holes in perovskite solar cells is an important factor in determining the energy conversion efficiency of cells. Small molecule hole transport materials have very good application potential in perovskite solar cells. Currently, high efficiency calcium and titanium Most of the mineral solar cells use the organic small molecule spiro-OMeTAD as a hole transporting material. However, the synthesis process is complicated, the cost is high, and the stability in air is poor. Therefore, low cost, easy preparation, high efficiency and high stability are developed. The organic hole transport material is an important research direction of perovskite solar cells.
Recently, under the support of the Chinese Academy of Sciences Pilot Project and the National Natural Science Foundation of China, Zhong Yuwu, a researcher at the Key Laboratory of Photochemistry of the Institute of Chemistry of the Chinese Academy of Sciences, and Hu Jinsong, a researcher at the Key Laboratory of Nanostructures and Nanotechnology, have developed a class of low-cost, It is easy to prepare two-dimensional conjugated organic small molecule hole transport material OMe-***yr, which is applied to perovskite solar cells to obtain an average energy conversion efficiency of 20%.
The researchers used four simple organic transformations to prepare OMe-***yr at 26% of total yield and gram scale. The current laboratory cost is about $50/g, which is more than half the cost of spiro-OMeTAD. Further optimize the synthesis step and reduce the cost. OMe-***yr has good solubility in common organic solvents and has good film forming properties. Thermal stability test shows that compound OMe-***yr has good thermal stability. It is suitable for the preparation of high stability optoelectronic devices. Electrochemical and spectroscopy studies show that the hole transport material energy level matches the ternary perovskite Cs0.05FA0.81MA0.14PbI2.55Br0.45 (CsMAFA) energy level. The introduction of the thiophene group in the compound OMe-***yr enhances the electron delocalization range of the molecule, stabilizes the HOMO level, and facilitates the injection of holes. In addition, due to the S in the OMe-***yr There is a certain Pb-S interaction between the atom and Pb in the perovskite, which can passivate surface defects in the perovskite crystal. The introduction of the thiophene group can improve the carrier transport ability and inhibit the interfacial recombination, and improve the device. Efficiency and weakening the hysteresis effect. Energy based on OMe-***yr-based perovskite solar cells The efficiency is up to 20.6% and the average energy conversion efficiency is 20.0%. The unpackaged device maintains an initial efficiency of 92% after 60 days of storage. Compound OMe-***yr is currently one of the few reported energy conversions. Hole transporting small organic molecules with an efficiency of more than 20% has a good application prospect. Related work was recently published in Angew. Chem. Int. Ed. 2018, 57, 10959, and by Sci. China Chem. (DOI: 10.1007 /s11426-018-9331-y) Highlights report. Relevant results have been applied for Chinese patent (patent application number: 201810185852.0).
