Controlled Synthesis Of NiO Nanocrystals And Their Applications For Solution Processed Optoelectronic Devices

Colloidal NiO and ITO nanocrystals are attractive functional materials due to the unique combination of solid-state properties and excellent solution dispersibility. They have been investigated as building blocks for low-cost and large-area solution-processed optoelectronic devices.The main results and conclusions are followings:1. We develop a LiSt assisted alcoholysis/aminolysis approach for NiO nanocrystals. Highly monodispersed NiO nanocrystals with the diamater of ca.2-5nm are prepared by the solution reaction. Lithium stearate, which is chemically stable, readily binds to the surfaces of oxide nanocrystals and can be easily removed, was employed as protecting ligand to suppress the reactivity of NiO nanocrystals and avoid their in-situ reduction to metal Ni particles. NaSt assisted reactions exhibited features similar to those of the LiSt assisted reactions. If additional LiSt was introduced into the aminolysis system of Copper(Ⅱ) acetylacetonate, Cu2O nanocrystals were obtained.2. The pure NiO nanocrystals were employed in bulk heterojunction organic photovoltaics (OPVs) and polymer light-emitting diodes (PLEDs), demonstrating the potential as high-quality hole-transporting interlayers (HTLs) for solution-processed optoelectronic devices as well as the compatibility with flexible electronics. The resulting solar cell devices show an average power conversion efficiency (PCE) of6.3%, which is a22%improvement over devices utilizing PEDOT:PSS HTLs. The PLED with NiO HTLs yield a maximum luminance of13500cd/m2at8V which is higher than that for PEDOT:PSS devices.3. ITO nanocrystals are successfully synthesized by a hot-injection strategy. In(ac)3and2-ethylhexanoaic were reacted to generate In(2-ethylhexanoate) as the indium precursor. The size and the LSPR peaks of ITO nanocrystals can be turned by controlling the Sn doped concentration. Tunning the Sn concentration from3%to30%, the LSPR peaks blue-shift from2100nm to1680nm, then red-shift to1930nm.