Current Mapping of Lead Phthalocyanine Thin Films in the Presence of Gaseous Dopants

Autor: Madhuri, Priya K., Santra, Pralay K, Bertram, Florian, John, Neena Susan
Jazyk: angličtina
Rok vydání: 2019
DOI: 10.3204/pubdb-2019-03488
Popis: Seminar, LEDANG, Malaysia; Physical chemistry, chemical physics 22, 10.1039.C9CP03873F (2019). doi:10.1039/C9CP03873F
The structural organization and its effect on conducting pathways in lead phthalocyanine(PbPc) thin films, a nonplanar phthalocyanine, deposited on Si and highly oriented pyrolyticgraphite (HOPG) substrates in the presence of iodine and ammonia vapors are presented. Thetwo-dimensional grazing incidence X-ray diffraction studies revealed that the crystallineordering in pristine PbPc films on Si and HOPG substrates have undergone a drastic molecularrearrangement and surface reconstruction up on iodine doping. The structural rearrangementleads to morphological changes and higher surface roughness in iodine doped PbPc (I-PbPc)films. An obvious enhancement in the current values of I-PbPc is attributed to the introduction ofholes as charge carriers. Nanoscale current mapping reveals the presence of percolationpathways in I-PbPc films, on both Si and HOPG substrates, responsible for the observed highconductance in contrast to the isolated conducting domains in the pristine PbPc system. A broaddistribution of current values across various conducting domains on Si is attributed to a mixtureof crystalline phases and disordered fractions of I-PbPc while a narrow distribution of currentvalues observed in the case of HOPG is attributed to the majorly disordered PbPc molecules.These films also show enhanced sensitivity towards ammonia by almost four times higher inmagnitude than pristine PbPc films. The current maps show that the adsorption of ammoniamolecules disrupts the iodine percolation pathways, thereby imposing a detrimental effect on theconductivity of the PbPc films.
Published by RSC Publ., Cambridge
Databáze: OpenAIRE
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