Doping Strategy for Efficient and Stable Triple Cation Hybrid Perovskite Solar Cells and Module Based on Poly(3-hexylthiophene) Hole Transport Layer.

As the hole transport layer (HTL) for perovskite solar cells (PSCs), poly(3-hexylthiophene) (P3HT) has been attracting great interest due to its low-cost, thermal stability, oxygen impermeability, and strong hydrophobicity. In this work, a new doping strategy is developed for P3HT as the HTL in triple-cation/double-halide ((FA1-x-y MAx Csy )Pb(I1-x Brx )3 ) mesoscopic PSCs. Photovoltaic performance and stability of solar cells show remarkable enhancement using a composition of three dopants Li-TFSI, TBP, and Co(III)-TFSI reaching power conversion efficiencies of 19.25% on 0.1 cm2 active area, 16.29% on 1 cm2 active area, and 13.3% on a 43 cm2 active area module without using any additional absorber layer or any interlayer at the PSK/P3HT interface. The results illustrate the positive effect of a cobalt dopant on the band structure of perovskite/P3HT interfaces leading to improved hole extraction and a decrease of trap-assisted recombination. Non-encapsulated large area devices show promising air stability through keeping more than 80% of initial efficiency after 1500 h in atmospheric conditions (relative humidity ≈ 60%, r.t.), whereas encapsulated devices show more than >500 h at 85 °C thermal stability (>80%) and 100 h stability against continuous light soaking (>90%). The boosted efficiency and the improved stability make P3HT a good candidate for low-cost large-scale PSCs.

A combined computational and experimental study of the [Co(bpy)3](2+/3+) complexes as one-electron outer-sphere redox couples in dye-sensitized solar cell electrolyte media.

A combined experimental and computational investigation conducted to understand the nature of the interactions between cobalt II/III redox mediators ([Co(bpy)3](2+/3+)) and their impact on the performance of the corresponding dye-sensitized solar cells (DSCs) is reported. The fully optimized equilibrium structures of cobalt(II/III)-tris-bipyridine complexes in the gas phase and acetonitrile solvent are obtained by the density functional B3LYP method using LanL2DZ and 6-31G(d,p) basis sets. The harmonic vibrational frequencies, infrared intensities and Raman scattering activities of the complexes are also calculated. The scaled computational vibrational wavenumbers show very good agreement with the experimental values. Calculations of the electronic properties of the complexes are also performed at the TD-B3LYP/6-31G(p,d)[LanL2DZ] level of theory. Detailed interpretations of the infrared and Raman spectra of the complexes in different phases are reported. Detailed atomic orbital coefficients of the frontier molecular orbitals and their major contributions to electronic excitations of the complexes are also reported. These results are in good agreement with the experimental electrochemical values. Marcus diagram is derived for the electron transfer reaction Co(II) + D35(+)→ Co(III) + D35 using the Co-N bond length as a reaction coordinate.

A universal co-solvent dilution strategy enables facile and cost-effective fabrication of perovskite photovoltaics.

Cost management and toxic waste generation are two key issues that must be addressed before the commercialization of perovskite optoelectronic devices. We report a groundbreaking strategy for eco-friendly and cost-effective fabrication of highly efficient perovskite solar cells. This strategy involves the usage of a high volatility co-solvent, which dilutes perovskite precursors to a lower concentration (<0.5 M) while retaining similar film quality and device performance as a high concentration (>1.4 M) solution. More than 70% of toxic waste and material cost can be reduced. Mechanistic insights reveal ultra-rapid evaporation of the co-solvent together with beneficial alteration of the precursor colloidal chemistry upon dilution with co-solvent, which in-situ studies and theoretical simulations confirm. The co-solvent tuned precursor colloidal properties also contribute to the enhancement of the stability of precursor solution, which extends its processing window thus minimizing the waste. This strategy is universally successful across different perovskite compositions, and scales from small devices to large-scale modules using industrial spin-coating, potentially easing the lab-to-fab translation of perovskite technologies.

High Efficiency MAPbI3 Perovskite Solar Cell Using a Pure Thin Film of Polyoxometalate as Scaffold Layer.

Here, we successfully used a pure layer of [SiW11 O39 ]8- polyoxomethalate (POM) structure as a thin-film scaffold layer for CH3 NH3 PbI3 -based perovskite solar cells (PSCs). A smooth nanoporous surface of POM causes outstanding improvement of the photocurrent density, external quantum efficiency (EQE), and overall efficiency of the PSCs compared to mesoporous TiO2 (mp-TiO2 ) as scaffold layer. Average power conversion efficiency (PCE) values of 15.5 % with the champion device showing 16.3 % could be achieved by using POM and a sequential deposition method with the perovskite layer. Furthermore, modified and defect-free POM/perovskite interface led to elimination of the anomalous hysteresis in the current-voltage curves. The open-circuit voltage decay study shows promising decrease of the electron recombination in the POM-based PSCs, which is also related to the modification of the POM/ perovskite interface and higher electron transport inside the POM layer.

Novel nanostructure zinc zirconate, zinc oxide or zirconium oxide pastes coated on fluorine doped tin oxide thin film as photoelectrochemical working electrodes for dye-sensitized solar cell.

Zinc zirconate (ZnZrO(3)) (ZZ), zinc oxide (ZnO) (ZO) and zirconium oxide (ZrO(2)) (ZRO) nano-particles were synthesized by simple sol-gel method. ZZ, ZO and ZRO nano-particles were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and UV-Vis diffuse reflectance spectrum (DRS). Nanoporous ZZ, ZO and ZRO thin films were prepared doctor blade technique on the fluorine-doped tin oxide (FTO) and used as working electrodes in dye sensitized solar cells (DSSC). Their photovoltaic behavior were compared with standard using D35 dye and an electrolyte containing [Co(bpy)(3)](PF(6))(2), [Co(pby)(3)](PF(6))(3), LiClO(4), and 4-tert-butylpyridine (TBP). The properties of DSSC have been studied by measuring their short-circuit photocurrent density (Jsc), open-circuit voltage (VOC) and fill factor (ff). The application of ZnZrO(3) as working electrode produces a significant improvement in the fill factor (ff) of the dye-sensitized solar cells (ff=56%) compared to ZnO working electrode (ff=40%) under the same condition.

Dye-sensitized solar cell characteristics of nanocomposite zinc ferrite working electrode: effect of composite precursors and titania as a blocking layer on photovoltaic performance.

This research investigates the performance of a zinc ferrite (ZF) as working electrodes in a dye-sensitized solar cell (DSSC). This ZF working electrode was prepared by sol-gel and thermal decomposition of four different precursors including: zinc acetate dihydrate (Zn(CH3COO)2·2H2O), ferric nitrate nonahydrate (Fe(NO3)3·9H2O), iron(III) acetate; Fe(C2H3O2)3, and zinc nitrate hexahydrate, Zn(NO3)2·6H2O. The effects of annealing temperature and precursors on the structural, morphological, and optical properties were investigated. The field emission scanning electron microscope images (FESEM) and scanning electron microscopy (SEM) show that ZFe films are polycrystalline in nature and homogeneous with densely packed grains. Nanoporous zinc ferrite coatings were prepared by doctor blade technique on the fluorine-doped tin oxide (FTO) and used as working electrodes in DSSC. In all DSSCs, platinized FTO and [Co(bpy)3](2+/3+) in 3-methoxy proponitrile were used as counter electrode and redox mediator system respectively. Comparing the fill factors of four different zinc ferrite nanocomposites, the highest fill factor was for ZnFe2O4-TBL sample. Cell fabricated with ZnFeA working electrode shows relatively higher Jsc.

Fabrication, characterization of two nano-composite CuO-ZnO working electrodes for dye-sensitized solar cell.

Two kind of CuO-ZnO nanocomposite working electrodes were synthesized by sol-gel technology and applied in dye-sensitized solar cells (DSSCs). Their characteristics were studied by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and UV-Vis diffuse reflectance spectrum (DRS). CuO-ZnO nanocomposite thin films were prepared doctor blade technique on the fluorine-doped tin oxide (FTO) and used as working electrodes in dye sensitized solar cells (DSSC). Their photovoltaic behavior were compared with standard using D35 dye and an electrolyte containing [Co(bpy)3](PF6)2, [Co(pby)3](PF6)3, LiClO4, and 4-tert-butylpyridine (TBP). The ranges of short-circuit current (JSC) from 0.18 to 0.21 (mA/cm(2)), open-circuit voltage (VOC) from 0.24 to 0.55V, and fill factor from 0.34 to 0.39 were obtained for the DSSCs made using the working electrodes. The efficiency of the working electrodes after the addition of TBL was more than doubled. The light scattering and carrier transport properties of these composites promote the performance of dye-sensitized solar cells (DSSCs).

A 1:1 cocrystal of 4-(dimethylamino)benzaldehyde and 6-phenyl-1,3,5-triazine-2,4-diamine.

The crystal structure of the title compound, C(9)H(11)NO.C(9)H(9)N(5), contains one molecule of each component in the asymmetric unit. Approximately planar clusters of four molecules are formed by N-H...N and N-H...O hydrogen bonds, and further N-H...N hydrogen bonds link adjacent clusters to form pleated ribbons. pi-pi interactions are found between triazine and aldehyde benzene rings in different clusters, generating stacks along the monoclinic b axis. The intramolecular geometry of the two components is similar to that found in other crystal structures containing these molecules. Both molecules are approximately planar, except for methyl H atoms, with a small twist about the C-C bond linking the phenyl and triazine rings.