牙1俳氏4‑1 (課程博士(英文))Date ofsubmission (month, day, year)
Deparhnent
MechanicalEnglneering
Applicant's name

StudentlD Number

フ.92018

12akiMasanobu

D 159105
Supe1ν】sors

SeijiYokoyama

Aye Myint Moh

Abstract (Doctor)
Title ofThesis

A

Study on Growth and characteristics ofThermaⅡy Evaporated orσanic semicon、ductorLayers(加熱蒸着した有機半導体層の成長と特性に関する研究)

rox.80o words

The 01'ganic semiconductors have been employed in electronics and optoelectronic devices be、Cause oftheir wide l'ange ofw'operties、 A great number of01'σanic matel'ials have been used as theactive layer for applications in organic electronics such as organic Hght emitting diodes (OLEDS),
Organic field effect tl'ansistors (OFETS), and organic photovoltaic devices (OPVS).01・oanic layers
have been prepared by using sevel'al methods ofsolution process such as spin‑coatinσ and vacuunl
Process such as vacU山n thermal evaporation. The structlu'e and qua1北y ofthe resultant orσanic layers
affects the performance ofthe electronic devices, and the am01'phous and bulk‑hetel・ojunction stNC‑
ture that was a nano‑scale mixture ofthe n・type and p‑type 01'ganic semiconductor have been em‑
Ployed fm' 0熔anic pv devices

Organic se111iconductors of π・conjugated S111a11 moleculeS 引'e 御'omisino and versatile organic
Semiconductors forthe electronics and optoelectronic devices induding 01'σanic pv devices because

Ofthe high mobility relating to the diffusion length ofthe carrier. The tl'anspolting phenomena of
the mobility is affected by the molecular arrangement in the 01'σanic sen]iconductm・1ayel・S, and tl〕earrangement ofthe thin layers insta11ed into the devices has been conu'0Ⅱed by adjusting the growth
including the 御'eparation technique, substrate and under‑1ayer material, and tl]e deposition rate. The
het飢'oepitaxial growth has been gen磁'aⅡy employed forthe fabrication of electronics and optoelec、
tl'onics devices constructed of inorganic semiconductors, and the la杜ice relationship at the hetero‑interface bet圦leen the layer and subS訂'ate material affects the atomic arl'an8ement of tl〕e l・esultant
イ︑

inorganic layer. The information and knowledge on the gl'owth of orσanic semiconductors is sti11
insufficient comP引'ed with that for inⅢ'σanic sen]iconduct01、SIn t11is thesis, the struct1Ⅱ'e ofsingle layers and bi・1ayers ofπ・conjugated smaⅡ molecules of27、dioctyl(1]b即ZothienoB,2・bHnb閉Zothiophene (C8・BTBT) and N,N'、dioctyl‑3,4,9,10、 polylenedi、Carboximide (PTCDI・C8) PI'ePω'ed on single C1うIstalsubstrates by avacuum thermal evaporation wasinvestigated with x・1'ay diffraction (XRD) and atomic force mi仇'oscopy (AFNI). The purpose ofthis
Wm'k isto charactel'ize the growth ofⅢ'oanic semiconductors includinσ the effects ofthe under‑1ayer
material and orientation and to w'opose the tentative 即'OW【h model applicable for the development
Ofnext generation π・conjugated sma11 molecular based devices
In chapter l,the back即'ound and purpose ofthis study lNas mentioned

In chapter 2, t1祀 Preferred orientation and 即'owth behavior of C8、BTBT deposited on quartz
glass, U 12のA・,(0001)C・, al02)R・single・cwstal A120.(sa即hirの,(10の・,知d (11D、single、cwstal
M旦O substrates wa'e investigated by xRD and AFM. The (0OD out、of、plane orientation with a
Similm'in‑plane orientation 、入las developed irrespective oftl]e substrate material and orientation, andthe de即'ee ofthe developlnent was reaected by the grain stluct山'e ofthe substrates

In chapter 3, effects ofule lay引'thickness and prePω'ation tempera加1'e ofthe C8‑BTBT layer onC・sapphire substrate on tl]e gr0工入亢h and chal'acteristics have been investig飢ed 工入lith xRD, AFNI, OP、
tical absm'ption measurement, and resistivity measure1ηent with and xNithout ligl〕t irradiation. TheC8・BTBT layers with tl〕e optical bandgap energy around 33 ev possessed the (0OD out、of、planeU

Orientation irrespective of the layer thickness and preparation tempera加re, The C8・BTBT layers
Were growing up in direction para11elto the substrate surface keepino almost constantheioht, and theContinuous layer was formed by the coalescence ofthe C8・BTBT grains、 The electricah'esistivity
decreased with in引'ease in the prePω'ation temperature due to the increase in the σrain size, and theHght irradiation induce the drastic decrease t042‑28 ΩCm. The tentative σrowth mechanism gov、
erned by π一π一stacking‑induced molecular 01'dering and diffusion ofmolecules on the substl'ates wasProposed based on the experimentalresults

In chapter 4, the prefen'ed orientation and structure ofpTCDI・C8 1ayers on the A1203 and N1σ0
Substrates W引'e investigated by xRD and AFM obseNation. The (0OD out・of・plane orientation wasdeveloped irrespective ofthe substrate material and orientation, and the continuous layer c0111Posed
Of needle・1ike 即'ains was fm'med atthe thichless of 15 nm f0110wed by the 即'ain σrowth with thethichless. The growth ofthe pTCDI・C8 1ayel' was similarto that for C8・BTBT layer, and the pro、Posed 即'owrh mechanisln is adequate to the pTCDI・C8 grolNth'毛︑In chaptet 5, the surface state of C8・BTBT/PTCDI・C8 bi・1ayerS 御'epared on c‑sapphire sub、Strate W飢'e investigated by xRD, AFM, and Kelvin Force Mi引'oscopy (KFM). The lattice relation、Ship of(001)・C8・BTBTガ(001)・PTCDI・C8 Was developed irrespective ofthe stacking ordel', butthe
C8・BTBT炉TCDI・C8 bi・1ayershowed an exceⅡent pelforlnance in the surface morph010σy and po、tel〕tialhomogeneity compared xuith the pTCDI・C8/C8・BTBT bi・1ayer, suggesting the hηPortance ofthe stackinσ m'derin the fab打Cation oftl〕e bi‑1ayer and the π一π、stacking‑induced molecular orderinσOfeach layer on the gl'owth

In chapter 6,the results obtained in this study was summarized. The tentative gl'OW[h mechanisn〕
Proposed based on the expe↑imental results 、入las adequate to the gl'owth ofthe single layel's and bi‑
Iayers of C8・BTBT and pTCDI・C8, and the gl'owth lnodel and experimental results obtained hereWi11SUPP011to the improvement ofthe performance offut山'e π・conjugated based organic semicon‑
ductor layel's and device fabrication for 01'ganic‑based applications

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