The Use of Size-Selective Excitation To Study Photocurrent through Junctions Containing Single-Size and Multi-Size Arrays of Colloidal CdSe Quantum Dots

Abstract

This paper describes a study of the generation and flow of photocurrent through junctions containing three-dimensional arrays of colloidal CdSe quantum dots (QDs) of either a single size or multiple sizes. The electrodes were indium tin oxide (ITO) covered with a thin layer of poly(3,4-ethylenedioxy-thiophene):poly(styrenesulfonate) (PEDOT:PSS) and a eutectic alloy of Ga and In (EGaIn). We measured the current-voltage characteristics of the junctions in the dark and under illumination, with various sources and wavelengths of excitation, and their photocurrent action spectra. Size-selective photoexcitation of the arrays of multiple sizes of QDs helped to determine (i) the location of the interface at which photoinduced separation of charge occurred, (ii) whether the energy absorbed by the QDs was redistributed before separation of charge, and (iii) the dependence of the photovoltage on the locations of various sizes of QDs within the junction. This research is a step toward the use of QDs for harvesting light and for transporting energy and charge in devices-for example, solar cells and photodetectors-that operate at zero bias.

Polymer Photovoltaic Cells Sensitive to the Circular Polarization of Light

“…This indicates that the efficiency of charge generation at the PEDOT:PSS/polymer interface is about two times lower compared to the polymer/C 60 interface. This finding is consistent with the efficient photoluminescence quenching at polymer/PEDOT:PSS interfaces22 and the photocurrent generation at CdSe quantum dot/PEDOT:PSS interfaces 23…”

Solution‐Processable Pyrite FeS2 Nanocrystals for the Fabrication of Heterojunction Photodiodes with Visible to NIR Photodetection

“…In the last decade, solution‐processed thin films consisting of semiconductor nanocrystals have demonstrated excellent optoelectronic performance with unique advantages of tunable absorption characteristics by the quantum confinement effect1–2 and enabling large‐area low‐cost fabrications 3–8. Among them, cadmium and lead chalcogenide (CdX and PbX) nanocrystals exhibited excellent optoelectronic performance in the harvesting of photons ranging from visible to infrared wavelengths 3, 9–11.…”

Synthesis and coherent vibrational laser spectroscopy of putative molecular constituents in isoprene-derived secondary organic aerosol particles

“…Despite this prominent role, SOA particle formation ranks among the least understood 5 processes in the atmosphere (Kanakidou et al, 2005;Hallquist et al, 2009;Goldstein and Galbally, 2007;Galbally et al, 2007;Weiss et al, 2008a), rooted in part in the limited knowledge about SOA chemical composition. Molecular studies (Yasmeen et al, 2010;Weiss et al, 2008b;Kleiber et al, 2009;Wang et al, 2005b;Gao et al, 2010;Mena-Carrasco et al, 2009;Huynh et al, 2003;Palaniappan et al, 2009;Greenham 10 et al, 1996;Sharma et al, 2003;Tolocka et al, 2004;Grassian, 2009;Docherty et al, 2005;Heaton et al, 2009) aimed at bridging this knowledge gap support the hypothesis that the products formed from the gas phase oxidization of biogenic volatile organic compounds react with one another to form species with lower and lower vapor pressures, ultimately leading to SOA particle formation. Heterogeneous processes such as 15 physisorption and surface reactions are important for conditions of condensational particle growth.…”