Multi-amine-assisted crystal growth of large-sized α-MoO3 elongated nano-plates.

Large-sized α-MoO3 elongated nano-plates were synthesized by the introduction of multi-amines such as ethylene di-amine and diethylene tri-amine (DETA) in the conventional hydrothermal reaction. DETA made large hexagonal rods with an h-MoO3 intermediate phase containing H2O, NH4OH, and DETA ions. During the hydrothermal reaction, the hexagonal rods were transformed to elongated α-MoO3 nano-plates by the re-dissolution of h-MoO3 and re-growth to α-MoO3 because DETA retarded the preferred growth reaction of the MoO6 octahedra to the [001] direction and helped the MoO6 octahedra to grow in the [100] direction. In addition, DETA promoted α-MoO3 nano-belts to be assembled into elongated nano-plates by oriented attachment because the multi-ammonium groups in the DETA backbone could adhere to the α-MoO3 nano-belts due to attractive Coulomb interactions.

Roles of SnX2 (X = F, Cl, Br) Additives in Tin-Based Halide Perovskites toward Highly Efficient and Stable Lead-Free Perovskite Solar Cells.

Preserving the stability of Sn-based halide perovskites is a primary concern in developing photovoltaic light-absorbing materials for lead-free perovskite solar cells. Whereas the addition of SnX2 (X = F, Cl, Br) has been demonstrated to improve the photovoltaic performance of Sn halide perovskite solar cells, the mechanistic roles of SnX2 in the performance enhancement have not yet been studied appropriately. Here we perform a comparative study of CsSnI3 films and devices and examine how SnX2 additives affect their stability, and the results are corroborated by first-principles-based theoretical calculations. Unlike the conventional belief that the additives annihilate defects, we find that the additives effectively passivate the surface and stabilize the perovskite phase, promoting the stability of CsSnI3. Our mechanism suggests that SnBr2, which shows ca. 100 h of prolonged stability along with a high power conversion efficiency of 4.3%, is the best additive for enhancing the stability of CsSnI3.

High-Performance Solid-State PbS Quantum Dot-Sensitized Solar Cells Prepared by Introduction of Hybrid Perovskite Interlayer.

High-performance solid-state PbS quantum dot-sensitized solar cells (QD-SSCs) with stable 9.2% power conversion efficiency at 1 Sun condition are demonstrated by introduction of hybrid perovskite interlayer. The PbS QDs formed on mesoscopic TiO2 (mp-TiO2) by spin-assisted successive precipitation and anionic exchange reaction method do not exhibit PbSO4 but have PbSO3 oxidation species. By introducing perovskite interlayer in between mp-TiO2/PbS QDs and poly-3-hexylthiophene, the PbSO3 oxidation species are fully removed in the PbS QDs and thereby the efficiency of PbS QD-SSCs is enhanced over 90% compared to the pristine PbS QD-SSCs.

Memory effect behavior with respect to the crystal grain size in the organic-inorganic hybrid perovskite nonvolatile resistive random access memory.

The crystal grain size of CH3NH3PbI3 (MAPbI3) organic-inorganic hybrid perovskite (OHP) film was controllable in the range from ~60 nm to ~600 nm by non-solvents inter-diffusion controlled crystallization process in dripping crystallization method for the formation of perovskite film. The MAPbI3 OHP non-volatile resistive random access memory with ~60 nm crystal grain size exhibited >0.1 TB/in2 storage capacity, >600 cycles endurance, >104 s data retention time, ~0.7 V set, and ~-0.61 V re-set bias voltage.