The carrier collection efficiency (ηc) and energy conversion efficiency (ηe) of polymer photovoltaic cells were improved by blending of the semiconducting polymer with C60 or its functionalized derivatives. Composite films of poly(2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene) (MEH-PPV) and fullerenes exhibit ηc of about 29 percent of electrons per photon and ηe of about 2.9 percent, efficiencies that are better by more than two orders of magnitude than those that have been achieved with devices made with pure MEH-PPV. The efficient charge separation results from photoinduced electron transfer from the MEH-PPV (as donor) to C60 (as acceptor); the high collection efficiency results from a bicontinuous network of internal donor-acceptor heterojunctions.

/pdf/polymer-photovoltaic-cells-enhanced-efficiencies-via-a-2lwj3yarfe.pdf

Polymer photovoltaic cells : enhanced efficiencies via a network of internal donor-acceptor heterojunctions

Energy harvested directly from sunlight offers a desirable approach toward fulfilling, with minimal environmental impact, the need for clean energy. Solar energy is a decentralized and inexhaustible natural resource, with the magnitude of the available solar power striking the earth’s surface at any one instant equal to 130 million 500 MW power plants.1 However, several important goals need to be met to fully utilize solar energy for the global energy demand. First, the means for solar energy conversion, storage, and distribution should be environmentally benign, i.e. protecting ecosystems instead of steadily weakening them. The next important goal is to provide a stable, constant energy flux. Due to the daily and seasonal variability in renewable energy sources such as sunlight, energy harvested from the sun needs to be efficiently converted into chemical fuel that can be stored, transported, and used upon demand. The biggest challenge is whether or not these goals can be met in a costeffective way on the terawatt scale.2

http://pubs.acs.org/doi/pdf/10.1021/cr1002326

Solar Water Splitting Cells

Evidence for photoinduced electron transfer from the excited state of a conducting polymer onto buckminsterfullerene, C(60), is reported. After photo-excitation of the conjugated polymer with light of energy greater than the pi-pi* gap, an electron transfer to the C(60) molecule is initiated. Photoinduced optical absorption studies demonstrate a different excitation spectrum for the composite as compared to the separate components, consistent with photo-excited charge transfer. A photoinduced electron spin resonance signal exhibits signatures of both the conducting polymer cation and the C(60) anion. Because the photoluminescence in the conducting polymer is quenched by interaction with C(60), the data imply that charge transfer from the excited state occurs on a picosecond time scale. The charge-separated state in composite films is metastable at low temperatures.

https://science.sciencemag.org/content/sci/258/5087/1474.full.pdf

Photoinduced electron transfer from a conducting polymer to buckminsterfullerene.

The interest in heterogeneous photocatalysis is intense and increasing, as shown by the number of publications on this theme which regularly appear in this journal, and the fact that over 2000 papers have been published on this topic since 1981. This article is an overview of the field of semiconductor photocatalysis : a brief examination of its roots, achievements and possible future. The semiconductor titanium dioxide (TiO 2 ) features predominantly in past and present work on semiconductor photocatalysis; as a result, in the most of the examples selected in this overview to illustrate various points the semiconductor is TiO 2 .

An overview of semiconductor photocatalysis

Preface Acknowledgements Notation Part I. Overview and Background Topics: 1. Introduction 2. Overview 3. Theoretical background 4. Periodic solids and electron bands 5. Uniform electron gas and simple metals Part II. Density Functional Theory: 6. Density functional theory: foundations 7. The Kohn-Sham ansatz 8. Functionals for exchange and correlation 9. Solving the Kohn-Sham equations Part III. Important Preliminaries on Atoms: 10. Electronic structure of atoms 11. Pseudopotentials Part IV. Determination of Electronic Structure, The Three Basic Methods: 12. Plane waves and grids: basics 13. Plane waves and grids: full calculations 14. Localized orbitals: tight binding 15. Localized orbitals: full calculations 16. Augmented functions: APW, KKR, MTO 17. Augmented functions: linear methods Part V. Predicting Properties of Matter from Electronic Structure - Recent Developments: 18. Quantum molecular dynamics (QMD) 19. Response functions: photons, magnons ... 20. Excitation spectra and optical properties 21. Wannier functions 22. Polarization, localization and Berry's phases 23. Locality and linear scaling O (N) methods 24. Where to find more Appendixes References Index.

Electronic Structure: Basic Theory and Practical Methods

A photonic integrated circuit implementing a receiver with an optical preamplifier and a wavelength filter for dense WDM systems has been fabricated. The integrated filter is based on planar optics and formed by a waveguide lens and Bragg grating combination. This arrangement provides a narrow filtering response of 0.4 nm and a high sidemode rejection ratio of 20 dB. A monolithically integrated preamplifier and photodetector are also incorporated to allow for high-sensitivity and high-speed operation. >

WDM receiver with integrated optical preamplifier, aspheric lens and grating filter

http://ieeexplore.ieee.org/iel3/68/6610/00262555.pdf

Controlled Nonlinearity Monolithic Integrated Optoelectronic Mixing Receiver

Multiwavelength transmission over 217 km of nondispersion shifted fibre is demonstrated at 1.7 Gbit/s using an integrated 16×1 laser/modulator array. Bit error rate performance is reported for single channel transmission using seven of the laser/modulators at discrete wavelengths from 1.545 to 1.555 μm. Additionally, electrical and optical crosstalk penalties are measured in a two channel WDM experiment.

1.7 Gbit/s transmission over 217 km using a 16*1 photonic integrated circuit transmitter

Digitally tunable laser based on the integration of a waveguide grating router and an optical amplifier

We report the fabrication of aspheric waveguide lenses on the InP/InGaAsP material system. A wide aperture (f/5) lens working at 1.5 times the diffraction limit is reported. Insertion loss below 1 dB is also measured. The lens is fabricated by a selective chemical etch of a planar waveguide and has potential applications in InP‐based photonic integrated circuits.

Barry Miller

Papers

WDM receiver with integrated optical preamplifier, aspheric lens and grating filter

Controlled Nonlinearity Monolithic Integrated Optoelectronic Mixing Receiver

1.7 Gbit/s transmission over 217 km using a 16*1 photonic integrated circuit transmitter

Digitally tunable laser based on the integration of a waveguide grating router and an optical amplifier

Aspheric waveguide lenses for photonic integrated circuits