ABSTRACTPolymer electrochemical cells have been reported to emit light. The current and light out... more ABSTRACTPolymer electrochemical cells have been reported to emit light. The current and light output increase rapidly with voltage, apparently beyond 2V. The polymer is an ionic conductor as well as an electronic (electron/hole) conductor, i.e. a mixed ionic-electronic conductor (MIEC).The I-V relations are explained here to be those of an MIEC of a particular defect model placed between two ion blocking electrodes. This MIEC defect model assumes a large concentration of mobile ions and small concentrations of electrons and holes. A p and an n region are formed in the MIEC. However, there is no space charge within the MIEC and it stays neutral. The resulting I-V relations are exponential. A good fit to the experimental data is obtained when electrode over-potential and heating of the polymer under current are taken into consideration.
... Mater. 2004, 16, 3688. [29] FM Winnik, H. Ringsdorf, J. Venzmer, Macromolecules 1990, 23, 241... more ... Mater. 2004, 16, 3688. [29] FM Winnik, H. Ringsdorf, J. Venzmer, Macromolecules 1990, 23, 2415. [30] HG Schild, M. Muthukumar, DA Tirrell, Macromolecules 1991, 24, 948. ... By Hossam Haick, Marianna Ambrico, Teresa Ligonzo, and David Cahen* ...
The journal of physical chemistry letters, Jan 2, 2015
High band gap, high open-circuit voltage solar cells with methylammonium lead tribromide (MAPbBr3... more High band gap, high open-circuit voltage solar cells with methylammonium lead tribromide (MAPbBr3) perovskite absorbers are of interest for spectral splitting and photoelectrochemical applications, because of their good performance and ease of processing. The physical origin of high performance in these and similar perovskite-based devices remains only partially understood. Using cross-sectional electron-beam-induced current (EBIC) measurements, we find an increase in carrier diffusion length in MAPbBr3(Cl)-based solar cells upon low intensity (a few percent of 1 sun intensity) blue laser illumination. Comparing dark and illuminated conditions, the minority carrier (electron) diffusion length increases about 3.5 times from Ln = 100 ± 50 nm to 360 ± 22 nm. The EBIC cross section profile indicates a p-n structure between the n-FTO/TiO2 and p-perovskite, rather than the p-i-n structure, reported for the iodide derivative. On the basis of the variation in space-charge region width with ...
The paper considers a photoelectrochemical cell with a polycrystalline thin-layer CdSe photoanode... more The paper considers a photoelectrochemical cell with a polycrystalline thin-layer CdSe photoanode in contact with a sulfur/sulfide redox couple in a basic solution. Pretreatment procedures for the titanium substrate and posttreatment procedures for the deposited CdSe layer are developed for the improvement of cell performance. Voltage losses due to polarization over the counter electrode are minimized with the use of several metal sulfides as electrocatalyzers, and simple low-cost production procedures have been developed for these counter electrodes. The feasibility of in situ storage of electrical energy with the use a third storage electrode is demonstrated.
ABSTRACT The electric potential distribution in dye-sensitized solar cells plays a major role in ... more ABSTRACT The electric potential distribution in dye-sensitized solar cells plays a major role in the operation of such cells. Models based on a built-in electric field which sets the upper limit for the open circuit voltage (Voc) and/or the possibility of a Schottky barrier at the interface between the mesoporous wide band gap semiconductor and the transparent conducting substrate have been presented. We show that I−V characteristics in the dark and upon illumination are very well explained by electron tunneling, rather than transport over a Schottky barrier, at this interface. Our calculations, based on tunnel currents, show that a discontinuity of the conduction band at the TiO2/FTO interface, rather than a built-in electric field, suffices for efficient electron transfer through this interface, and, thus, for efficient operation of this type of solar cell. Clearly, this will hold only if the photoinduced electrostatic potential barrier between the transparent conducting substrate and the mesoporous wide band gap semiconductor drops over a region that is sufficiently narrow to allow efficient tunneling through it.
ABSTRACTPolymer electrochemical cells have been reported to emit light. The current and light out... more ABSTRACTPolymer electrochemical cells have been reported to emit light. The current and light output increase rapidly with voltage, apparently beyond 2V. The polymer is an ionic conductor as well as an electronic (electron/hole) conductor, i.e. a mixed ionic-electronic conductor (MIEC).The I-V relations are explained here to be those of an MIEC of a particular defect model placed between two ion blocking electrodes. This MIEC defect model assumes a large concentration of mobile ions and small concentrations of electrons and holes. A p and an n region are formed in the MIEC. However, there is no space charge within the MIEC and it stays neutral. The resulting I-V relations are exponential. A good fit to the experimental data is obtained when electrode over-potential and heating of the polymer under current are taken into consideration.
... Mater. 2004, 16, 3688. [29] FM Winnik, H. Ringsdorf, J. Venzmer, Macromolecules 1990, 23, 241... more ... Mater. 2004, 16, 3688. [29] FM Winnik, H. Ringsdorf, J. Venzmer, Macromolecules 1990, 23, 2415. [30] HG Schild, M. Muthukumar, DA Tirrell, Macromolecules 1991, 24, 948. ... By Hossam Haick, Marianna Ambrico, Teresa Ligonzo, and David Cahen* ...
The journal of physical chemistry letters, Jan 2, 2015
High band gap, high open-circuit voltage solar cells with methylammonium lead tribromide (MAPbBr3... more High band gap, high open-circuit voltage solar cells with methylammonium lead tribromide (MAPbBr3) perovskite absorbers are of interest for spectral splitting and photoelectrochemical applications, because of their good performance and ease of processing. The physical origin of high performance in these and similar perovskite-based devices remains only partially understood. Using cross-sectional electron-beam-induced current (EBIC) measurements, we find an increase in carrier diffusion length in MAPbBr3(Cl)-based solar cells upon low intensity (a few percent of 1 sun intensity) blue laser illumination. Comparing dark and illuminated conditions, the minority carrier (electron) diffusion length increases about 3.5 times from Ln = 100 ± 50 nm to 360 ± 22 nm. The EBIC cross section profile indicates a p-n structure between the n-FTO/TiO2 and p-perovskite, rather than the p-i-n structure, reported for the iodide derivative. On the basis of the variation in space-charge region width with ...
The paper considers a photoelectrochemical cell with a polycrystalline thin-layer CdSe photoanode... more The paper considers a photoelectrochemical cell with a polycrystalline thin-layer CdSe photoanode in contact with a sulfur/sulfide redox couple in a basic solution. Pretreatment procedures for the titanium substrate and posttreatment procedures for the deposited CdSe layer are developed for the improvement of cell performance. Voltage losses due to polarization over the counter electrode are minimized with the use of several metal sulfides as electrocatalyzers, and simple low-cost production procedures have been developed for these counter electrodes. The feasibility of in situ storage of electrical energy with the use a third storage electrode is demonstrated.
ABSTRACT The electric potential distribution in dye-sensitized solar cells plays a major role in ... more ABSTRACT The electric potential distribution in dye-sensitized solar cells plays a major role in the operation of such cells. Models based on a built-in electric field which sets the upper limit for the open circuit voltage (Voc) and/or the possibility of a Schottky barrier at the interface between the mesoporous wide band gap semiconductor and the transparent conducting substrate have been presented. We show that I−V characteristics in the dark and upon illumination are very well explained by electron tunneling, rather than transport over a Schottky barrier, at this interface. Our calculations, based on tunnel currents, show that a discontinuity of the conduction band at the TiO2/FTO interface, rather than a built-in electric field, suffices for efficient electron transfer through this interface, and, thus, for efficient operation of this type of solar cell. Clearly, this will hold only if the photoinduced electrostatic potential barrier between the transparent conducting substrate and the mesoporous wide band gap semiconductor drops over a region that is sufficiently narrow to allow efficient tunneling through it.
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