Observation of phase-retention behavior of the HC(NH2)2PbI3 black perovskite polymorph upon mesoporous TiO2 scaffolds.

The α→δ phase transition, which occurs favorably in planar films of a black α-HC(NH2)2PbI3 (α-FAPbI3) perovskite in the amibent, is retarded when α-FAPbI3 is deposited upon mesoporous TiO2 scaffolds. It is hypothesized that this is due to the synergistic effect of the partial encapsulation of α-FAPbI3 by the mesoporous TiO2 and the elevated activation energy for the transition reaction associated with the substantial increase of the TiO2/α-FAPbI3 interfacial area in the mesoscopic system.

Intercalation crystallization of phase-pure α-HC(NH2)2PbI3 upon microstructurally engineered PbI2 thin films for planar perovskite solar cells.

The microstructure of the solid-PbI2 precursor thin film plays an important role in the intercalation crystallization of the formamidinium lead triiodide perovskite (α-HC(NH2)2PbI3). It is shown that microstructurally engineered PbI2 thin films with porosity and low crystallinity are the most favorable for conversion into uniform-coverage, phase-pure α-HC(NH2)2PbI3 perovskite thin films. Planar perovskite solar cells fabricated using these thin films deliver power conversion efficiency (PCE) up to 13.8%.

Manipulating Crystallization of Organolead Mixed-Halide Thin Films in Antisolvent Baths for Wide-Bandgap Perovskite Solar Cells.

Wide-bandgap perovskite solar cells (PSCs) based on organolead (I, Br)-mixed halide perovskites (e.g., MAPbI2Br and MAPbIBr2 perovskite with bandgaps of 1.77 and 2.05 eV, respectively) are considered as promising low-cost alternatives for application in tandem or multijunction photovoltaics (PVs). Here, we demonstrate that manipulating the crystallization behavior of (I, Br)-mixed halide perovskites in antisolvent bath is critical for the formation of smooth, dense thin films of these perovskites. Since the growth of perovskite grains from a precursor solution tends to be more rapid with increasing Br content, further enhancement in the nucleation rate becomes necessary for the effective decoupling of the nucleation and the crystal-growth stages in Br-rich perovskites. This is enabled by introducing simple stirring during antisolvent-bathing, which induces enhanced advection transport of the extracted precursor-solvent into the bath environment. Consequently, wide-bandgap planar PSCs fabricated using these high quality mixed-halide perovskite thin films, Br-rich MAPbIBr2, in particular, show enhanced PV performance.

Development of 1,1'-oxalyldiimidazole chemiluminescent biosensor using the combination of graphene oxide and hairpin aptamer and its application.

Highly sensitive biosensor with 1,1'-oxalyldiimidazole chemiluminescence (ODI-CL) detection was developed to rapidly quantify Vibrio (V) parahaemolyticus without time-consuming procedures such as multiple long-incubations and washings. When V. parahaemolyticus in Tris-HCl (pH 7) and hairpin DNA aptamer conjugated with TEX615 in DNA free deionized water were consecutively added in PBS buffer (pH 7.4) containing graphene oxides (GOs), V. parahaemolyticus and GOs bind competitively to hairpin DNA aptamer conjugated with TEX615 during 10 min of incubation at room temperature. Brightness of light immediately emitted with the addition of ODI-CL reagents (e.g., ODI, H2O2) after the incubation was dependent on the concentration of V. parahaemolyticus in a sample. The dynamic range of linear calibration curve for the quantification of V. parahaemolyticus in a sample was from 4375 to 70,000 cells/ml. The limit of detection (LOD = background + 3 × standard deviation, 2230 cells/ml) of the biosensor operated with good accuracy, precision, and recovery was lower than those of conventional assay methods such as time-consuming and expensive enzyme-linked immunosorbent assays.