Accession Number:

ADA604628

Title:

Structural and Electrical Functionality of NiO Interfacial Films in Bulk Heterojunction Organic Solar Cells

Descriptive Note:

Journal article

Corporate Author:

NORTHWESTERN UNIV EVANSTON IL DEPT OF MATERIALS SCIENCE AND ENGINEERING

Report Date:

2011-04-01

Pagination or Media Count:

11.0

Abstract:

The functionality of NiO interfacial layers in enhancing bulk heterojunction BHJ organic photovoltaic OPV cell performance is investigated by integrated characterization of the electrical properties, microstructure, electronic structure, and optical properties of thin NiO films grown on glassITO electrodes. These NiO layers are found to be advantageous in BHJ OPV applications due to favorable energy band levels, interface passivation, p-type character, crystallinity smooth surfaces, and optical transparency. The NiO overlayers are fabricated via pulsed-laser deposition and found to have a work function of 5.3 eV. They are investigated by both topographic and conductive atomic force microscopy and shown to passivate interfacial charge traps. The films also have an average optical transparency of 80 in the visible range, crucial for efficient OPV function, and have a near-stoichiometric NiO surface composition. By grazing-incidence X-ray diffraction, the NiO thin films are shown to grow preferentially in the 111 direction and to have the fcc NaCl crystal structure. Diodes of p-n structure and first-principles electronic structure calculations indicate that the NiO interlayer is preferentially conductive to holes, with a lower hole charge carrier effective mass versus that of electrons. Finally, the implications of these attributes in advancing efficiencies for state-of-the-art OPV systems--in particular, improving the open circuit voltage VOC--are discussed.

Subject Categories:

  • Electric Power Production and Distribution

Distribution Statement:

APPROVED FOR PUBLIC RELEASE