A P3HT/fullerene based bulk heterojunction solar cell is one of the most prominent candidates for a polymer solar cell, but the efficiency is limited by poor long wavelength absorption. One way to increase the conversion efficiency is to modify the active layer absorption by the addition of materials, that increase the absorption light in the red and infrared spectral region. Possible materials are inorganic quantum dots (QDs). In the present study we choose InP/ZnS quantum dots with an emission peak wavelength of about 660 nm. Additionally we addded multiwalled carbon nanotubes in order to favor charge carrier separation and enhances the lateral conduction of the films. The films have been deposited by spin coating in a non conducting polymer matrix (PMMA) in order to investigate the interplay between the quantum dots and the carbon nanotube and their electrical conductivity independently of the future host material in the polymer solar cell. We kept the QD concentration constant and varied the concentration of the CNTs in the deposited films. The characterization of the film morphology by SEM imaging and of the optical properties by photoluminescence and transmittance revealed a rather complex interplay between nanotubes and quantum dots. In particular we found a strong tendency of the nanotubes with high concentration of CNTs to agglomerate in spherical configuration. Electrical conductivity measurements in coplanar and sandwich configuration enabled to verify the degree of increase of the sample conductivity by the nanotube addition. In particular the measurements in sandwich configuration, where the PMMA/CNT films have been deposited directly on a crystalline silicon substrate, revealed the formation of a type of Schottky diode and a monotonic decrease of the conduction inset voltage with increasing CNT content. The homogeneity of the films is still poor, which has been revealed by photoluminescence imaging.
Investigation of the optical and electrical characteristics of a combination of InP/ZnS-quantum dots with MWCNTs in a PMMA matrix
G. Landi;NEITZERT, Heinrich Christoph
2012-01-01
Abstract
A P3HT/fullerene based bulk heterojunction solar cell is one of the most prominent candidates for a polymer solar cell, but the efficiency is limited by poor long wavelength absorption. One way to increase the conversion efficiency is to modify the active layer absorption by the addition of materials, that increase the absorption light in the red and infrared spectral region. Possible materials are inorganic quantum dots (QDs). In the present study we choose InP/ZnS quantum dots with an emission peak wavelength of about 660 nm. Additionally we addded multiwalled carbon nanotubes in order to favor charge carrier separation and enhances the lateral conduction of the films. The films have been deposited by spin coating in a non conducting polymer matrix (PMMA) in order to investigate the interplay between the quantum dots and the carbon nanotube and their electrical conductivity independently of the future host material in the polymer solar cell. We kept the QD concentration constant and varied the concentration of the CNTs in the deposited films. The characterization of the film morphology by SEM imaging and of the optical properties by photoluminescence and transmittance revealed a rather complex interplay between nanotubes and quantum dots. In particular we found a strong tendency of the nanotubes with high concentration of CNTs to agglomerate in spherical configuration. Electrical conductivity measurements in coplanar and sandwich configuration enabled to verify the degree of increase of the sample conductivity by the nanotube addition. In particular the measurements in sandwich configuration, where the PMMA/CNT films have been deposited directly on a crystalline silicon substrate, revealed the formation of a type of Schottky diode and a monotonic decrease of the conduction inset voltage with increasing CNT content. The homogeneity of the films is still poor, which has been revealed by photoluminescence imaging.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
