3.1. Fundamental Characterization 6672 3.2. Photocurrent Action Spectroscopy 6673 3.3. Optical Characterization 6673 3.4. Characterization of Electron Transfer 6673 4. Electron Transport in Metal Oxide Films 6674 4.1. Mechanism of Photoinduced Carrier Transport 6674 4.2. Characterization of Diffusion Length 6675 4.3. One-Dimensional (1-D) Transport Architectures 6675 4.4. Electrolyte Interactions 6676 5. Recent Trends in Liquid-Junction Solar Cells 6676 5.1. Dye Sensitized Solar Cells 6677 5.2. Quantum Dot Sensitized Solar Cells 6678 5.3. Carbon Nanostructure Based Photochemical Solar Cells 6679

Beyond Photovoltaics: Semiconductor Nanoarchitectures for Liquid-Junction Solar Cells

Influence of CO2 on the oxygen permeation performance and the microstructure of perovskite-type (Ba0.5Sr0.5)(Co0.8Fe0.2)O3−δ membranes

Solar photoproduction of hydrogen: A review

Metal oxide photoelectrodes for hydrogen generation using solar radiation-driven water splitting

The occurrence of simple solid-state displacement reactions during mechanical alloying has been investigated. The reduction of cupric oxide to pure copper metal by a variety of metallic reducing agents was studied, and the powders were examined by X-ray diffractometry and electron microscopy. When milled with a liquid process control agent, the reaction progressed gradually with time, whereas an unstable combustion reaction occurred when no such control agent was employed. A minimum adiabatic temperature of 1300 K is necessary for combustion to occur in these systems. The reaction enthalpy is an important factor in determining the precombustion period. The as-milled powders consisted of finely divided, nanometer-sized crystallites with an extremely high defect density. It is proposed that the increased reactivity of the system arises through the unique conditions prevailing during mechanical alloying.

Displacement reactions during mechanical alloying

Recombination in Solar Cells: Theoretical Aspects- 1 Introduction- 2 Conventions Usually Made for p-n Junctions and Solar Cells- 3 Three Laws of Photovoltaics- 4 Maximum Power, Recombination and the Ideality Factor- 5 Junction Currents as Recombination Currents- 6 Steady-State Recombination Rates at a Given Plane X- 7 Junction Model and Space-Dependences- 8 Transition Region Recombination Current Density- 9 The Bulk-Regions Recombination Current Density- 10 Summery of p-n Junction Current Densities from Sections 8 and 9- 11 Configuration and Electrostatics of the Schottky Barrier Solar Cell- 12 The Place of Recombination Effects in (p-type) Schottky Barrier Solar Cells- 13 Recombination Currents and Voltage Drops in (p-type) Schottky Barrier Solar Cells- 14 Conclusion- A Few More General Topics- (I) Thermodynamic Efficiency- (II) Simple Theory to See that an Optimum Energy Gap Exists- (III) Is Dollars per Peak Watt a Good Unit?- (IV) Energy Unit for Global Use- (V) When will Solar Conversion be Economically Viable?- References- Schottky Barrier Solar Cells- 1 Introduction- 2 The Schottky Barrier Cell Principle- 21 Principle of SBSC Operation- 22 Current Transport Mechanism in Schottky Barriers- 23 Effect of the MIS Potential Distribution upon the Diode Quality Factor n- 24 The MIS SBSC under Illumination- 25 The Minority Carrier MIS SB Cell- 3 Solar Cell Parameters and Design Considerations- 31 Metal-Semiconductor Barrier Height- 32 Diode Quality Factor n- 33 Interfacial Oxide Thickness- 34 Transmission Properties of the Metal- 35 Spectral Response- 36 Substrate Resistivity- 37 Substrate Thickness- 38 Series Resistance- 4 Results and Discussion of Typical Silicon MIS Cells- 41 Open Circuit Voltage- 42 Short Circuit Current Density- 43 Fill Factor- 44 Efficiency- 45 The Min MIS Cell- 46 The MIS Inversion Layer Cell- 47 Stability of MIS Solar Cells- 48 The Future for MIS Cells - Cheaper Substrates?- Acknowledgement- References- CdS-Cux S Thin Film Solar Cells- 1 Introduction- 2 CdS Thin Film Technology- 21 Vacuum Vapor Deposition of CdS Films- 22 Sputtering- 23 Spray Deposition- 24 Sintering- 3 CuxS Thin Film Technology- 31 Dipping Process (Wet Process)- 32 Evaporation of CuCl- 33 Evaporation of CuxS- 34 Sputtering of CuxS- 4 Properties of the CdS Layer- 41 Crystallography and Grain Size of CdS Films- 42 Optical Properties of the CdS Films- 43 Luminescence- 44 Electrical Properties of CdS Films- 5 Properties of CuxS Films- 51 Stoichiometry- 52 Coulometric Titration- 53 Optical Properties- 54 Electrical Properties- 6 Properties of the Heterojunction- 61 Structure of the Heterojunction- 62 Surface Effects of the CuxS Film- 63 Capacitance Measurements- 64 Diffusion Length in CuxS and CdS- 65 Spectral Response- 66 Band Diagram- 7 Technology of CdS-CuxS Photovoltaic Generators- 71 Cell Structures- 72 Fabrication Process of CdS-CuxS Cells- 8 Performance Characteristics of Solar Cells and Generators- References- Conversion of Solar Energy Using Tandem Photovoltaic Cells Made from Multi-Element Semiconductors- I Introduction- II Increasing Efficiency by Recourse to Tandem PV Cell Systems- III Design of an Optimized Solar Cell Structure for Tandem Cell Systems- IV Selection of Semiconductors for Tandem Solar Cell Systems- V Optimized Design of Direct Gap Photovoltaic Cells- VI Monolothic and Split Spectrum Tandem Cell Systems- VII Synthesis and Properties of Ternary Alloy Chalcopyrite Semiconductors- VIII Thin Films of CuInSe2 and Solar Cells Made from Them- IX Summary and Conclusions- References- The Principles of Photoelectrochemical Energy Conversion- I Sunlight Conversion into Chemical Energy- Photoredox Reactions- Redox Energies and the Scales of Redox Potentials- Photosynthesis as an Example- Artificial Systems for Energy Conversion- References to Lecture for Further Reading- II Fundamentals of Semiconductor Electrochemistry- The Space Charge Layer- Kinetics of Electron Transfer Reactions- References- III The Semiconductor Electrolyte Contact under Illumination and Photodecomposition Reactions- Distribution of Electrons and Holes under Illumination- Photodecomposition of Semiconductors- References- IV Photoelectrochemical Cells and their Problems- Regenerative Cells- Storage Cells- Energy Conversion Efficiency- References- Photoelectrochemical Devices for Solar Energy Conversion- General Discussion of Photoelectrochemical Devices- Semiconductor Electrolyte Junctions - Conventional Picture- Photo-Induced Charge Transfer Reactions- Semiconductor Electrode Stability- Electrochemical Photovoltaic Cells- Photoelectrosynthetic Cells- Photoelectrolysis Cells- Photocatalytic Cells- General Considerations- Effects and Importance of Surface States- Unpinned Band Edges- Hot Carriers- Surface Modification- Electrochemical Photovoltaic Cells- Reduced Surface and Grain Boundary Recombination- Non-aqueous Electrolytes- Storage Systems- General Status and Prognosis for Electrochemical Photovoltaic Cells- Photoelectrosynthetic Cells- Derivatized Electrodes- Photo-Oxidation and Photo-Reduction on the same Surface and in Particulate System- Dye Sensitization- Layered Compounds and other New Materials- General Status and Prognosis for Photoelectrosynthesis- Acknowledgement- References- The Iron Thionine Photogalvanic Cell- The Reaction Scheme- The Differential Equation- The Characteristic Lengths- The Kinetic Length- Bleaching and the Generation Length- The Recipe for Success- The Electrode Kinetics- Current Voltage Characteristics- Homogeneous Kinetics- The Iron Thionine System- The Reaction Scheme- Quantum Efficiencies- The Parameters- Rotating Transparent Disc Electrodes- The Thionine System- The Synthesis of Modified Thiazine Dyes- The Properties of the Modified Dyes- Self Quenching- Summary of Progress to Date- Electrode Selectivity- The Problem- The Manufacture of the Thionine Coated Electrode- Properties of the Thionine Coated Electrode- Electrode Kinetics- Application to Photogalvanic Systems- The Efficiencies of Photogalvanic Cells- The Concentration of Fe(II)- The Concentration of Ee(III)- The Variation of Power with ?E? and k-2- Variation with pH- Final Summary- Acknowledgements- References- Charge Separation and Redox Catalysis in Solar Energy Conversion Processes- 1 Introduction- 2 Design of Photoredox Reactions for Photodissociation of Water- 21 Photodecomposition of Water in Homogeneous Solutions- 22 Photoproduction of H2 from Water- 221 Photolysis of Simple Ions in Acid Media- 222 Photolysis of Metal Hydrides- 223 H2 Production via Dye-Sensitized Redox Reactions- 224 Photochemistry of Selected Redox Systems for H2 Evolution- 23 Redox Systems for O2-Evolution from Water- 231 Photo-Induced Oxygen Evolution from Water- 3 Stabilization of Redox Intermediates through the Use of Multiphase Systems- 31 Micelles- 311 Photoionisation- 312 Light Induced Electron Transfer in the Micelle- 313 Solution and Spatial Separation of Reactants in Micelles- 314 Functional Micellar Systems- a) Redox Reactions in Transition Metal Ion Micelles- b) Micelles Formed with Crown Ether Surfactants- c) Micelles with Long Chain Derivatives of Sensitizer or Acceptor Relays- 32 Light-Induced Charge Separation in Vesicles- 33 Charge Separation Phenimena in Other Multiphase Systems- 4 Redox Catalysis- 41 Concept of Redox Catalysis- 42 Redox Catalysis in the H2 -Evolution Reaction from Water- 43 Redox Catalysis in the O2Evolution Reaction from Water- 44 Coupled Redox Catalysts for Water Decomposition- 5 Photoelectrochemical Cells Based on Redox Reactions- References- Author Index

Photovoltaic and Photoelectrochemical Solar Energy Conversion

The study of factors which influence the reactivity of solids is of both practical and fundamental importance. Obviously, the control of reaction rates is a main practical objective in solid-state chemistry. In some cases the interest is in having reactivities as high as possible, such as with solid propellants or with heterogeneous catalysts. In other instances, on the contrary, the aim is to lower the reactivity; a well-known example here is the oxidation and corrosion of metals. In still other cases, such as in the manufacture of solid-state electronic devices, preferential reaction at chosen parts of a solid surface is wanted. As for the fundamental aspect, it is essentially by systematically studying the factors on which the reaction rate depends that the corresponding mechanism can be established. However, our purpose in this chapter is not to show how reaction mechanisms are derived, but to try and draw a generalized picture accounting for the effects of various factors on solid-state reactivity. Consequently, the accepted mechanisms, whenever available, will be used as a basis for discussing the action of factors which influence the reaction rates.

Willy Dekeyser

Papers

Photovoltaic and Photoelectrochemical Solar Energy Conversion

Factors Influencing the Reactivity of Solids