Application of ZnxLayFezO4 spinel nanomaterial in quantum dot sensitized solar cells

摘要： A novel inorganic spinel nanomaterial with formula Zn0.6093La1.3979Fe0.8650O4 (ZLF) was synthesized and characterized by the X-ray photoelectron spectroscopy (XPS) to determine its stoichiometric formula. The Filed-Emission Scanning Electron Microscopy (FE-SEM) and Transmission Electron Microscopy (TEM) images displayed that the ZLF nanoparticles (NPs) had a very fine spherical morphology and average particle sizes in the range of about 5–30 nm. Quantum dot-sensitized solar cells (QDSSCs) were fabricated using the ZLF NPs which were incorporated into the TiO2 pastes of photoanodes. The photoluminescence (PL) spectra of the ZLF NPs and the photoanodes exhibited three maxima plus a weak broad peak at around 420, 460 and 485 plus 530 nm. The lowest intensity of the PL peak for the CdSe cell fabricated using 0.4 %ZLF suggested that it had the least charge recombination and the easiest electron transfer. The photovoltaic parameters of the optimized champion cell containing 0.4 % of ZLF NPs (η = 3.50 %, JSC = 13.11 mA/cm2, VOC = 0.58 V) were boosted compared to those of the ZLF-free reference cell (η = 2.18 %, JSC = 8.70 mA/cm2, VOC = 0.57 V) demonstrating a high improvement of approximately 61 % in the efficiency. The Electrochemical Impedance Spectra (EIS) revealed that the charge transfer resistance (RCT) in the optimum cell was dropped by adding the ZLF NPs into the TiO2 compared to that of the reference ZLF-free cell. Thus, upon adding 0.4 %ZLF, appropriate photocurrent efficiency was attained for the QDSSC because the ZLF nanoparticles were used in a minimum amount in order to speed up the electron transport, decline the recombination and enhance the cell efficiency.