Inorganic CuFeO2 Delafossite Nanoparticles as Effective Hole Transport Materials for Highly Efficient and Long-Term Stable Perovskite Solar Cells.

The regular architecture (n-i-p) of perovskite solar cells (PSCs) has attracted increasing interest in the renewable energy field, owing to high certified efficiencies in the recent years. However, there are still serious obstacles of PSCs associated with spiro-OMeTAD hole transport material (HTM), such as (i) prohibitively expensive material cost (∼150-500 $/g) and (ii) operational instability at elevated temperatures and high humidity levels. Herein, we have reported the highly photo, thermal, and moisture-stable and cost-effective PSCs employing inorganic CuFeO2 delafossite nanoparticles as a HTM layer, for the first time. By exhibiting superior hole mobility and additive-free nature, the best-performing cell achieved a power conversion efficiency (PCE) of 15.6% with a negligible hysteresis. Despite exhibiting a lower PCE as compared to the spiro-OMeTAD-based control cell (19.1%), nonencapsulated CuFeO2-based cells maintained above 85% of their initial efficiency, while the PCE of control cells dropped to ∼10% under continuous illumination at maximum power point tracking after 1000 h. More importantly, the performance of control cells was quickly degraded at above 70 °C, whereas CuFeO2-based cells, retaining ∼80% of their initial efficiency after 200 h, were highly stable even at 85 °C in ambient air under dark conditions. Besides showing significant improvement in stability against light soaking and thermal stress, CuFeO2-based cells exhibited superior shelf stability even at 80 ± 5% relative humidity and retained over 90% of their initial PCE. Overall, we strongly believe that this study highlights the potential of inorganic HTMs for the commercial deployment of long-term stable and low-cost PSCs.

Hydrogen sulphate-based ionic liquid-assisted electro-polymerization of PEDOT catalyst material for high-efficiency photoelectrochemical solar cells.

This work reports the facile, one-step electro-polymerization synthesis of poly (3,4-ethylenedioxythiophene) (PEDOT) using a 1-ethyl-3-methylimidazolium hydrogen sulphate (EMIMHSO4) ionic liquid (IL) and, for the first time its utilization as a counter electrode (CE) in dye-sensitized solar cells (DSSCs). Using the IL doped PEDOT as CE, we effectively improve the solar cell efficiency to as high as 8.52%, the highest efficiency reported in 150 mC/cm2 charge capacity, an improvement of ~52% over the control device using the bare PEDOT CE (5.63%). Besides exhibiting good electrocatalytic stability, the highest efficiency reported for the PEDOT CE-based DSSCs using hydrogen sulphate [HSO4]- anion based ILs is also higher than platinum-(Pt)-based reference cells (7.87%). This outstanding performance is attributed to the enhanced charge mobility, reduced contact resistance, improved catalytic stability, smoother surface and well-adhesion. Our experimental analyses reveal that the [HSO4]- anion group of the IL bonds to the PEDOT, leading to higher electron mobility to balance the charge transport at the cathode, a better adhesion for high quality growth PEDOT CE on the substrates and superior catalytic stability. Consequently, the EMIMHSO4-doped PEDOT can successfully act as an excellent alternative green catalyst material, replacing expensive Pt catalysts, to improve performance of DSSCs.

Penternary chalcogenides nanocrystals as catalytic materials for efficient counter electrodes in dye-synthesized solar cells.

The penternary chalcogenides Cu2CoSn(SeS)4 and Cu2ZnSn(SeS)4 were successfully synthesized by hot-injection method, and employed as a catalytic materials for efficient counter electrodes in dye-synthesized solar cells (DSSCs). The structural, compositional, morphological and optical properties of these pentenary semiconductors were characterized by X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), energy-dispersive spectrometer (EDS) and ultraviolet-visible (UV-Vis) spectroscopy. The Cu2CoSn(SeS)4 and Cu2ZnSn(SeS)4 nanocrystals had a single crystalline, kesterite phase, adequate stoichiometric ratio, 18-25 nm particle sizes which are forming nanospheres, and band gap energy of 1.18 and 1.45 eV, respectively. Furthermore, the electrochemical impedance spectroscopy and cyclic voltammograms indicated that Cu2CoSn(SeS)4 nanocrystals as counter electrodes exhibited better electrocatalytic activity for the reduction of iodine/iodide electrolyte than that of Cu2ZnSn(SeS)4 nanocrystals and conventional platinum (Pt). The photovoltaic results demonstrated that DSSC with a Cu2CoSn(SeS)4 nanocrystals-based counter electrode achieved the best efficiency of 6.47%, which is higher than the same photoanode employing a Cu2ZnSn(SeS)4 nanocrystals (3.18%) and Pt (5.41%) counter electrodes. These promising results highlight the potential application of penternary chalcogen Cu2CoSn(SeS)4 nanocrystals in low-cost, high-efficiency, Pt-free DSSCs.

Development of a highly sensitive MIP based-QCM nanosensor for selective determination of cholic acid level in body fluids.

Determination of cholic acid is very important and necessary in body fluids due to its both pharmaceutical and clinical significance. In this study, a quartz crystal microbalance (QCM) nanosensor, which is imprinted cholic acid, has been developed for the assignation of cholic acid. The cholic acid selective memories have been generated on QCM electrode surface by using molecularly imprinted polymer (MIP) based on methacryloylamidohistidine-copper (II) (MAH-Cu(II)) pre-organized monomer. The cholic acid imprinted nanosensor was characterized by atomic force microscopy (AFM) and then analytical performance of the cholic acid imprinted QCM nanosensor was studied. The detection limit was found to be 0.0065µM with linear range of 0.01-1,000 µM. Moreover, the high value of Langmuir constant (b) (7.3*10(5)) obtained by Langmuir graph showed that the cholic acid imprinted nanosensor had quite strong binding sites affinity. At the last step of this procedure, cholic acid levels in body fluids were determined by the prepared imprinted QCM nanosensor.

Preparation of MIP-based QCM nanosensor for detection of caffeic acid.

In the present work, a new caffeic acid imprinted quartz crystal microbalance (QCM) nanosensor has been designed for selective assignation of caffeic acid in plant materials. Methacrylamidoantipyrine-iron(III) [MAAP-Fe(III)] as metal-chelating monomer has been used to prepare selective molecular imprinted polymer (MIP). MIP film for detection of caffeic acid has been developed on QCM electrode and selectivity experiments and analytical performance of caffeic acid imprinted QCM nanosensor has been studied. The caffeic acid imprinted QCM nanosensor has been characterized by AFM. After the characterization studies, imprinted and non-imprinted nanosensors was connected to QCM system for studies of connection of the target molecule, selectivity and the detection of amount of target molecule in real samples. The detection limit was found to be 7.8 nM. The value of Langmuir constant (b) (4.06 × 10(6)) that was acquired using Langmuir graph demonstrated that the affinity of binding sites was strong. Also, selectivity of prepared caffeic acid imprinted nanosensor was found as being high compared to chlorogenic acid. Finally, the caffeic acid levels in plant materials was determined by the prepared QCM nanosensor.