The Study Of Interfacial Electronic Structures For Organic Tandem Solar Cell And Perovskite Solar Cell

Currently, exploiting new energies and expanding the application of renewable energies are one of the most promising methods to solve the energy crisis, as well as protect our environment. As one of new energy and renewable energy, solar energy can bring lots of financial profits and environmental profits, which has a very promising future. This is the reason why solar cell devices are always a hot research topic from time to time. In order to get high power conversion efficiency and reliable stability, it is necessary to conduct thorough studies of device work mechanism and structure design for organic solar cell and perovskite solar cell.As is well known, interface plays a vital role in the device characteristics, and a comprehensive understanding of interface is quit favorable to improve device performance. In this thesis, the interfaces, including the interconnection layers of organic tandem cell as well as the interface between hole transport or extraction layer and CH3NH3PbIBr2 were studied by using photoelectron emission spectrometer, and the detailed characterizations were gotten.The electronic structures of organic interconnectors, consisting of cesium fluoride-doped 4,7-diphenyl-1,10-phenanthroline and hexaazatriphenylene-hexacarbonitrile(HATCN), had been investigated via in situ photoemission spectroscopy. The experimental determination shows that the HATCN interlayer plays a significant role in the interface energetics with a dramatic decrease in the reverse built-in potential for electrons and holes from stacked subcells, which is beneficial to the charge recombination between HATCN and the adjacent layer. In accordance with the energy-level alignments, the open-circuit voltage of tandem OSC incorporating a HATCN-based interconnector is almost 2 times that of a single-cell OSC, revealing the effectiveness of the HATCN-based interconnectors in tandem organic devices and verifying the correct prediction from the interface results.The hybrid interfaces between lead halide perovskite and organic hole-transport materials(HTMs) had been studied by using in situ ultraviolet and X-ray photoemission techniques. The measured alignment schemes at perovskite/HTM hybrid interfaces reveal different energy level offsets with respect to the variation of HTMs, including spiro-ometad(2,2′-7,7′-tetrakis( N, N di-p-me-thoxyphenyla-mine)-9,9′-spirobifl uorene)、HATCN and NPB(N,N ′-di(naphthaEne-1-yl)- N, N ′-diphenylbenzidine).It is identified that spiro-ometad and NPB are suitable to facilitate the interfacial hole extraction. HATCN can’t act as the hole extraction layer, which is opposite to predication.Using photoelectron emission spectrometer as the interface characterization methods, it can be greatly helpful to design and optimize the solar cell devices as well as to avoid some subjective mistakes. The mechanism of high efficiency device could also be revealed from the perspective of interface. At the end, I hope these results would be informative for the development of organic tandem solar cell and perovskite solar cell.