Low-Energy Inverse Photoemission Study on the Electron Affinities of Fullerene Derivatives for Organic Photovoltaic Cells

The lowest unoccupied molecular orbital (LUMO) levels of six fullerene derivatives frequently used for organic photovoltaic cells are examined in the solid state. We employed a new experimental technique, low-energy inverse photoemission spectroscopy (LEIPS), which allows us to determine the electron affinities of solid samples within the uncertainties of 0.1 eV. Using the precisely determined electron affinities, the energy difference between the ionization energy of donor and the electron affinity of acceptor is compared with the open circuit voltage for various polymer/fullerene combinations taken from the literature. The result suggests that the well-known relation between the energy difference and the open circuit voltage should be reconsidered

Electron Transport in Bathocuproine Interlayer in Organic Semiconductor Devices

When a thin layer of bathocuproine (BCP) is inserted between the metal electrode and the organic layer of the organic semiconductor device, the electron injection/collection efficiency at the interface is significantly improved. However, the mechanism of electron transport through the BCP layer has not been clarified yet. In this study, we directly observed the unoccupied electronic states of the Ag/BCP interface using low-energy inverse photoemission spectroscopy. The result shows that Ag strongly interacts with the BCP molecule and the lowest unoccupied molecular orbital (LUMO) level of the Ag-BCP complex aligns with the Fermi level, indicating that the electron transport occurs through the LUMO level of the complex. With the aid of DFT calculation, we identify the reaction product

Visualization 2: High-speed driving of liquid crystal lens with weakly conductive thin films and voltage booster

Video taken during advanced driving. Originally published in Applied Optics on 20 September 2015 (ao-54-27-8145

Example of fitting of arterial and portal-venous curves and tissue enhancement curves with various models.

<p>Graphs illustrate examples of (A and B) fitting of the arterial and portal input enhancement curves, (C and D) fitting of the five different models to a voxel enhancement curve which was sampled from the HCC, and (E and F) their corresponding impulse response curves (i.e., <i>Q</i>_T(<i>t</i>) = (<i>F</i>/<i>V</i>_T) ⋅ <i>R</i>_T(<i>t</i>)) where two different cases are shown in the left and right columns. WX = water-exchange-modified, TK = Tofts-Kety, ETK = extended Tofts-Kety. 2CX = two compartment exchange, AATH = adiabatic approximation to tissue homogeneity, and DP = distributed parameter.</p

Results of univariate Cox’s proportional hazards regression analysis of parameters in terms of overall survival.

<p>Note.—WX = water-exchange-modified, TK = Tofts-Kety, ETK = extended Tofts-Kety, 2CX = two compartment exchange, AATH = adiabatic approximation to the tissue homogeneity, DP = distributed parameter, <i>BF</i> = total hepatic blood flow (in mL/min/100 g), <i>γ</i> = arterial flow fraction (unitless), <i>BF</i>_A = arterial blood flow (in mL/min/100 g), <i>BF</i>_PV = portal blood flow (in mL/min/100 g), <i>BV</i> = blood volume (in mL/100 g), <i>MTT</i> = mean transit time (in min), <i>PS</i> = capillary wall permeability-surface area product (in mL/min/100 g), <i>v</i>_I = fractional interstitial volume (unitless), <i>E</i> = extraction fraction (unitless), <i>τ</i>_C = mean intracellular water molecule lifetime (sec), and <i>v</i>_C = fractional intracellular volume (unitless). Bold numbers with asterisk (*) indicate a statistically significant difference in the 1000 permutation test for hazard ratio in univariate Cox proportional hazards analysis (two-sided <i>P</i><0.05).</p><p>Results of univariate Cox’s proportional hazards regression analysis of parameters in terms of overall survival.</p

Symbols and definitions for kinetic parameters.

<p>Symbols and definitions for kinetic parameters.</p

Parameter values derived from the five different WX kinetic models.

<p>Note.—SD = standard deviation, WX = water-exchange-modified, TK = Tofts-Kety, ETK = extended Tofts-Kety, 2CX = two compartment exchange, AATH = adiabatic approximation to the tissue homogeneity, DP = distributed parameter, <i>BF</i> = total hepatic blood flow (in mL/min/100 g), <i>γ</i> = arterial flow fraction (unitless), <i>BF</i>_A = arterial blood flow (in mL/min/100 g), <i>BF</i>_PV = portal blood flow (in mL/min/100 g), <i>BV</i> = blood volume (in mL/100 g), <i>MTT</i> = mean transit time (in min), <i>PS</i> = capillary wall permeability-surface area product (in mL/min/100 g), <i>v</i>_I = fractional interstitial volume (unitless), <i>E</i> = extraction fraction (unitless), <i>τ</i>_C = mean intracellular water molecule lifetime (sec), <i>v</i>_C = fractional intracellular volume (unitless), and <i>RMSE</i> = root-mean-square error between original and fitted <i>E</i>_T(<i>t</i>).</p><p>Parameter values derived from the five different WX kinetic models.</p

Example of kinetic parameter maps derived from various models.

<p>Parametric maps of total hepatic blood flow (<i>BF</i>), arterial flow fraction (<i>γ</i>), arterial blood flow (<i>BF</i>_A), portal blood flow (<i>BF</i>_PV), blood volume (<i>BV</i>), mean transit time (<i>MTT</i>), capillary wall permeability-surface area product (<i>PS</i>), fractional interstitial volume (<i>v</i>_I), extraction fraction (<i>E</i>), mean intracellular water molecule lifetime (<i>τ</i>_C), and fractional intracellular volume (<i>v</i>_C) for HCC in (A) a low-risk man aged 52 years who survived for 23.87 months, and (B) a high-risk man aged 72 years who survived for 8.53 months. WX = water-exchange-modified, TK = Tofts-Kety, ETK = extended Tofts-Kety, 2CX = two compartment exchange, AATH = adiabatic approximation to tissue homogeneity, and DP = distributed parameter.</p

Kaplan-Meier curves for kinetic parameters predictive of 1-year survival.

<p>Cross-validated Kaplan-Meier plots for (A) arterial flow fraction (<i>γ</i>) and (B) fractional interstitial volume (<i>v</i>_I) derived from the water-exchange-modified Tofts-Kety (WX-TK) model, and (C) mean intracellular water molecule lifetime (<i>τ</i>_C) and (D) fractional intracellular volume (<i>v</i>_C) derived from the water-exchange-modified extended Tofts-Kety (WX-ETK) model. Survival of patients with advanced HCC treated with sunitinib was better with <i>γ</i> over 0.833 and <i>v</i>_I over 0.300 in the WX-TK model, and with <i>τ</i>_C at most 0.927 sec and <i>v</i>_C at most 0.611 in the WX-ETK model.</p

Optimal cut-off values of parameters and their log-rank test results from leave-one-out cross-validated Kaplan-Meier analysis in terms of 1-year survival.

<p>Note.—WX = water-exchange-modified, TK = Tofts-Kety, ETK = extended Tofts-Kety, 2CX = two compartment exchange, AATH = adiabatic approximation to the tissue homogeneity, DP = distributed parameter, <i>BF</i> = total hepatic blood flow (in mL/min/100 g), <i>γ</i> = arterial flow fraction (unitless), <i>BF</i>_A = arterial blood flow (in mL/min/100 g), <i>BF</i>_PV = portal blood flow (in mL/min/100 g), <i>BV</i> = blood volume (in mL/100 g), <i>MTT</i> = mean transit time (in min), <i>PS</i> = capillary wall permeability-surface area product (in mL/min/100 g), <i>v</i>_I = fractional interstitial volume (unitless), <i>E</i> = extraction fraction (unitless), <i>τ</i>_C = mean intracellular water molecule lifetime (sec), and <i>v</i>_C = fractional intracellular volume (unitless). Bold numbers with asterisk (*) indicate a statistically significant difference in the 1000 log-rank permutation test (two-sided <i>P</i><0.05).</p><p>Optimal cut-off values of parameters and their log-rank test results from leave-one-out cross-validated Kaplan-Meier analysis in terms of 1-year survival.</p