No abstract

There have been many reports on the application of pyrene derivatives as organic semiconductors, but 1,8subsituted pyrene semiconductors are less well-developed. Twop -type 1,8-substituted pyrene derivatives were synthesized that were composed of apyrene core, thiopheneorb ithiophene arms, and end-capped octyl chains.T hese structures weren ot completely symmetrical and the dihedral angles between the pyrene core and the adjacent thiophene units had ad ifferenceo fapproximately two degrees. The field-effect performance of these materials was tested on a variety of dielectric surfaces. The performance of both materials with as pin-coated polystyrene layer on SiO 2 (PS-treated SiO 2 )w as better than that with an octadecyltrichlorosilane self-assembled monolayer on SiO 2 (OTS-treated SiO 2 ), which was mainly attributed to the presence of large grains on the low-leakage and high-capacitance PS films. The thiophenecontained compound presented ah ole mobility of up to 0.18 cm 2 V À1 s À1 on PS-treated SiO 2 ,w hich was 45 times that of the bithiophene-contained compound, owing to less steric hindrance, high crystallinity,and largegrain size.

Despite the fact that power conversion efficiency (PCE) has been greatly improved in recent years, perovskite solar cells (PSCs) need to overcome some challenges, like stability, for the commercial application. Herein, an anionic conjugated polyelectrolyte, sulfonic-containing polyfluorene (abbreviated to SPF), has been developed to modify the interface between the electron-transporting layer (ETL) SnO2 and the optoelectronic active layer MAPbI3 in the n-i-p cells. After 40 days of storage in atmospheric environment in the dark with exposure to a controlled humidity of about 10%, PCE of the SPF-modified cells with the structure of ITO/SnO2/SPF/MAPbI3/spiro-OMeTAD/Au still remained 94% of the initial value. In contrast, the control cell without SPF only remained 31.1% of its initial efficiency after 29 days. The main reason for the stability enhancement is the adjustment of interfacial energy level, the crystallinity enhancement, and the removal of the interfacial defect of the perovskite layer by introducing the hydrophobic and smooth SPF interfacial layer. Deep electrical study on the PSCs discloses that the cell has low carrier transfer resistance, low leakage current density, and minor interfacial charge accumulation. What’s more, the short-circuit current density is improved, and PCE of 20.47% is achieved.