Study On The Self-n-Doping And Self-Assembly Of Fullerene Ammonium Salts

Organic solar cells (OSCs) and organic-inorganic metal halide perovskite solar cells (pero-SCs) have been considered as two promising photovoltaic technologies due to their advantages of solution-processing, simple device structure and possibility to be fabricated into large-area flexible devices. Recently, fullerene and fullerene derivatives, as a kind of ideal cathode interlayer material, have played an important role in solar cells for their n-type semiconductor character and higher electron mobility, which not only can enhance the power conversion efficiency (PCE) of photovoltaic device, but also can improve the overall stability of the device. On the basis of previous research work, self-n-doping and self-assembly of fullerene ammonium salts with different anions were studied systematically. This paper has three main aspects as followed:1. Based on the research of the structure-property relationship of fullerene ammonium iodide (PCBANI), the self-doping characteristics and structures of another two kinds of fullerene ammonium salts (PCBANBr and PCBANC1) were characterized. The doping effects and influence factors of conductivity were further explored.2. An unprecedented supramolecular system of self-n-doped PCBANI was constructed through a delicate balance among iodide anion-?, electrostatic, and C60 ?-? interactions. The self-assembly layer structure of ordered fullerenes were characterized and clarified by several characterization methods, such as XRD, HRTEM, FESEM, XPS and computational modeling. An iodide-linked C6o ?-? two-dimensional (2-D) network was established by the formation of intermolecular iodide anion-? interactions between iodide and the surrounded fullerene cores. Consequently, the ordered and tightly packed fullerenes sandwiching iodide could facilitate electron transfer along the network system. Through testing with electron-only devices and OFET, the self-assembled PCBANI film exhibits significantly high conductivity compared to its disordered counterpart, manifests the importance of the ?-extended network for electron transfer.3. The self-assembly behaviors of other fullerene ammonium salts (PCBDANI, PCBANBr, PCBANBr-P and PCBANC1) have been studied, which make contrbution to the development of controlling self-assembled architectures and new applications of this kind of fullerene derivatives.This work provides a key strategy to control the packing of ordered electron-transport materials to suppress defect formation. Moreover, engineering self-assembly of self-n-doped fullerenes with novel architectures, such as nanowire, nanotube, and nanoparticle would yield new functionalities that are suitable for photovoltaic devices, nanoelectronics, etc.