TY - JOUR
T1 - Exploring the Formation and Growth of Organic Semiconductors with mm-Scale Grains
AU - Rand, Barry P.
AU - Fusella, Michael A.
AU - Shayegan, Komron
AU - Dull, Jordan T.
N1 - Funding Information:
This work was supported by the National Science Foundation Award No. ECCS-1709222.
Publisher Copyright:
© 2018 SID.
PY - 2018
Y1 - 2018
N2 - While record mobilities have been reported for organic semiconductors in their single crystal form, the bulk nature of such crystals prohibit their practical application in devices. Here, we discuss our efforts to realize pinhole free films of organic semiconductors with grains of up to 1 mm in extent. One such material is rubrene, but we will also show our efforts on other materials applicable to organic light emitting diodes, such as the electron transport layer 2,2’,2”-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi). For rubrene, we will show our efforts to understand crystal formation, epitaxy, and transistors. Homoepitaxial studies uncover evidence of point and line defect formation in these films, indicating that homoepitaxy is not at equilibrium or strain-free. Point defects that are resolved as screw dislocations can be eliminated under closer-to-equilibrium conditions, whereas we are not able to eliminate the formation of line defects. We are, however, able to eliminate these line defects by growing on a bulk single crystal of rubrene, indicating that the line defects are a result strain built into the thin film template, indicating that, in general, organic crystalline thin films may not adopt the exact lattice of a bulk crystal. Transistors made out of these large-grained films of rubrene display charge carrier mobility of up to 3.5 cm2 V–1 s–1, very close to single crystal values, highlighting their potential for practical application.
AB - While record mobilities have been reported for organic semiconductors in their single crystal form, the bulk nature of such crystals prohibit their practical application in devices. Here, we discuss our efforts to realize pinhole free films of organic semiconductors with grains of up to 1 mm in extent. One such material is rubrene, but we will also show our efforts on other materials applicable to organic light emitting diodes, such as the electron transport layer 2,2’,2”-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi). For rubrene, we will show our efforts to understand crystal formation, epitaxy, and transistors. Homoepitaxial studies uncover evidence of point and line defect formation in these films, indicating that homoepitaxy is not at equilibrium or strain-free. Point defects that are resolved as screw dislocations can be eliminated under closer-to-equilibrium conditions, whereas we are not able to eliminate the formation of line defects. We are, however, able to eliminate these line defects by growing on a bulk single crystal of rubrene, indicating that the line defects are a result strain built into the thin film template, indicating that, in general, organic crystalline thin films may not adopt the exact lattice of a bulk crystal. Transistors made out of these large-grained films of rubrene display charge carrier mobility of up to 3.5 cm2 V–1 s–1, very close to single crystal values, highlighting their potential for practical application.
KW - crystals
KW - organic semiconductor
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U2 - 10.1002/SDTP.12587
DO - 10.1002/SDTP.12587
M3 - Conference article
AN - SCOPUS:85140255273
SN - 0097-966X
VL - 49
SP - 413
EP - 414
JO - Digest of Technical Papers - SID International Symposium
JF - Digest of Technical Papers - SID International Symposium
IS - 1
T2 - SID Symposium, Seminar, and Exhibition 2018, Display Week 2018
Y2 - 20 May 2018 through 25 May 2018
ER -