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Title:The external bias-dependent electric field at hole-injecting electrode/[alpha]-NPD junction and its relationship to Gaussian disordered interface states
Authors:ID Cvikl, Bruno (Author)
Files:.pdf The_external_bias-dependent_electric_field_Cvikl_2019.pdf (1004,22 KB)
MD5: 96515299D065D9ED4667467CA6347072
 
URL https://www.fe.um.si/e-jet/38-2019/2060-december-2019.html
 
Language:English
Work type:Scientific work
Typology:1.01 - Original Scientific Article
Organization:FE - Faculty of Energy Technology
Abstract:An alternative interpretation of two different sets of published temperature-dependent current-voltage a-NPD (i.e. N,N'-Di(1-naphthyl)-N,N'-diphenyl-(1,11-biphenyl)-4,4'-diamine) organic semiconductor data is presented. The measurements are described in terms of the hole drift current density expressed with two parameters: the electric field at the hole-injecting interface, Eint, and, ?max, the hole mobility determined by the measured current density at the maximum value of the externally applied electric field, Ea, in a given experiment. The former parameter, depending on the contact résistance, may be a function of Ea but the latter is Ea independent, The fixed value of Eint signifies the occurrence of the space charge limited current, SCLC, within the electrode/a-NPD structures and the contact is ohmic. Then, the calculated weak bias-dependent hole drift mobility, a function of Eint, equals the well%known exponential bias-dependent mobility, and saturates. The data not displaying SCLC characteristics are used for the calculation of Eint dependence on the applied field, Ea. It is shown that the quasi-ohmic contacts cause Eint to become a strong double-valued function of the externally applied electric field, Ea, described in terms of the distorted, inverted, high order parabola. The corresponding bias-dependent hole drift mobility is non-exponential and evolves on a considerably lower level than in SCLC cases. It is found that a sufficiently increased Ea alters the quasi-ohmic contact/a-NPD region into the ohmic one. A simple model of a thin, net hole charged, electrode/a-NPD interface enables the relationship between the deduced interfacial electric field, Eint, and the Ea dependent Gaussian width, as well as the energy shift of its peak along the negative binding energy is to be investigated. The currentvoltage method appears to be a helpful expedient for the investigation of the electric field at hole-injecting electrode/organic interfaces.
Keywords:electrode/organic electric field, contact affected hole mobility, organic interface disorder parameters
Publication status:Published
Publication version:Version of Record
Publication date:01.12.2019
Publisher:Fakulteta za energetiko Univerze v Mariboru
Year of publishing:2019
Number of pages:Str. 11-37
Numbering:Letn. 12, Št. 4
PID:20.500.12556/DKUM-86626 New window
UDC:537.212
ISSN on article:1855-5748
COBISS.SI-ID:1024385884 New window
Publication date in DKUM:22.12.2023
Views:572
Downloads:7
Metadata:XML DC-XML DC-RDF
Categories:Misc.
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Record is a part of a journal

Title:Journal of energy technology
Publisher:Fakulteta za energetiko
ISSN:1855-5748
COBISS.SI-ID:243311360 New window

Secondary language

Language:Slovenian
Title:Od zunanje napetosti odvisno električno polje ob stiku vrzeli vbrizgajoče elektrode/[alfa]-NPD in povezava z neurejenimi energijskimi stanji vmesne plasti
Abstract:Članek podaja alternativno fizikalno interpretacijo dveh primerov v literaturi objavljenih temperaturno odvisnih meritev gostote toka v odvisnosti od pritisnjene napetosti na vzorcih a-NPD (i. e. N,N' -Di(1-naftil)-N,N'-difenil-(1,1'-bifenil)-4,4'-diamin) organskega polprevodnika. Meritve gostote toka vrzeli so v pričujočem članku popisane z dvema parametroma: z jakostjo električnega polja, Eint, na vmesni plasti elektroda/organski polprevodnik kjer se vrzeli vbrizgavajo v organski medij in, umax, mobilnost vrzeli, ki je določena z izmerjeno gostota toka pri maksimalni vrednosti zunanje električne poljske jakosti, Ea, danega eksperimenta. Parameter, Eint, ki je funkcija kontaktne napetosti, lahko zavisi še od Ea, toda drugi parameter je od Ea neodvisna konstanta. Nespremenjena vrednost Eint z vrednostjo Ea podaja obstoj t. im. omejenega toka zaradi prostorskega naboja, SCLC, v vzorcu a-NPD s čimer je tedaj električni kontakt opredeljen kot ohmski stik. V tem primeru je izračunana, šibko Ea, odvisna mobilnost vrzeli podana z dobro poznano eksponentno odvisnostjo, ki vodi do nasičenja mobilnosti vrzeli. Eksperimentalni podatki, ki ne zadoščajo merilom SCLC so uporabljeni za izračun odvisnosti Eint od zunanjega polja Ea. Izkaže se, da zaradi kvazi-ohmskega kontakta postane Eint dvolična funkcija zunanjega pritisnjenega polja Ea, ki zavzame obliko skrivljene in invertirane parabole višjega reda. Temu ustrezna mobilnost vrzeli se izraža v ne-eksponentni formi is zavzame vrednosti, ki so bistveno pod nivojem vrednosti izračunane v primerih opredeljenih z SCLC značilnostmi. V delu je pokazano, da je mogoče z dovolj velikim zunanjim poljem, Ea, preoblikovati kvazi-ohmski kontakt v ohmskega. Poenostavljeni model tenke, z vrzeli nasičene, vmesne plasti elektroda/a-NPD omogoča proučevanje vzajemnega odnosa med električnim poljem vmesne plasti Eint in od Ea odvisno širino Gaussove funkcije razmazanosti energijskih stanj vrzeli v organskem polprevodniku in pa energijski pomik le-te vzdolž negativne vezavne energije. Eksperimentalna metoda gostota toka - napetost se izkaže, kot nadvse ustrezna metoda za raziskave električne poljske jakosti z vbrizganimi vrzeli odlikovane vmesne plasti stika elektrode/organski polprevodnik.
Keywords:električno polje, meritve gostote toka, fizika, parametri motenj na organskem vmesniku


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  1. Journal of energy technology

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