Investigation of Thermally Induced Degradation in CHNHPbI Perovskite Solar Cells using In-situ Synchrotron Radiation Analysis.

In this study, we employ a combination of various in-situ surface analysis techniques to investigate the thermally induced degradation processes in MAPbI perovskite solar cells (PeSCs) as a function of temperature under air-free conditions (no moisture and oxygen). Through a comprehensive approach that combines in-situ grazing-incidence wide-angle X-ray diffraction (GIWAXD) and high-resolution X-ray photoelectron spectroscopy (HR-XPS) measurements, we confirm that the surface structure of MAPbI perovskite film changes to an intermediate phase and decomposes to CHI, NH, and PbI after both a short (20 min) exposure to heat stress at 100 °C and a long exposure (>1 hour) at 80 °C. Moreover, we observe clearly the changes in the orientation of CHNH organic cations with respect to the substrate in the intermediate phase, which might be linked directly to the thermal degradation processes in MAPbI perovskites.

Relationship between ion migration and interfacial degradation of CHNHPbI perovskite solar cells under thermal conditions.

Organic-inorganic hybrid perovskite solar cells (PSCs) have been extensively studied because of their outstanding performance: a power conversion efficiency exceeding 22% has been achieved. The most commonly used PSCs consist of CHNHPbI (MAPbI) with a hole-selective contact, such as 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9-spiro-bifluorene (spiro-OMeTAD), for collecting holes. From the perspective of long-term operation of solar cells, the cell performance and constituent layers (MAPbI, spiro-OMeTAD, etc.

Design Principle and Loss Engineering for Photovoltaic-Electrolysis Cell System.

The effects of exchange current density, Tafel slope, system resistance, electrode area, light intensity, and solar cell efficiency were systematically decoupled at the converter-assisted photovoltaic-water electrolysis system. This allows key determinants of overall efficiency to be identified. On the basis of this model, 26.

Integration of electro-optic polymer modulators with low-loss fluorinated polymer waveguides.

We have demonstrated a hybrid Mach-Zehnder optical modulator consisting of a large-core, low-loss fluorinated passive polymer waveguide and an electro-optic (EO) polymer waveguide. The combination exhibits low fiber coupling loss to the passive waveguide and reduced transmission loss because the EO polymer waveguide is used only in the active region. The two waveguides are connected by vertical tapers that permit low-loss adiabatic coupling between the two modes.