TY - JOUR
T1 - Metal Composition and Polyethylenimine Doping Capacity Effects on Semiconducting Metal Oxide-Polymer Blend Charge Transport
AU - Huang, Wei
AU - Guo, Peijun
AU - Zeng, Li
AU - Li, Ran
AU - Wang, Binghao
AU - Wang, Gang
AU - Zhang, Xinan
AU - Chang, Robert P.H.
AU - Yu, Junsheng
AU - Bedzyk, Michael J.
AU - Marks, Tobin J.
AU - Facchetti, Antonio
N1 - Funding Information:
Cohen X-ray Diffraction Facility, EPIC facility, Keck-II facility, and SPID facility of the NUANCE Center at Northwestern University, which received support from the MRSEC program (NSF DMR-1720139), the International Institute for Nanotechnology (IIN), the Keck Foundation, and the State of Illinois. A.F. thanks the Shenzhen Peacock Plan project (KQTD20140630110339343) for support. W.H. and B.W. thank the joint-Ph.D. program supported by the China Scholarship Council for fellowships.
Funding Information:
We thank AFOSR (FA9550-15-1-0044), the Northwestern University MRSEC (NSF DMR-1720139), and Flexterra Corp. for support of this research. This work made use of the J. B.
Publisher Copyright:
© 2018 American Chemical Society.
PY - 2018/4/25
Y1 - 2018/4/25
N2 - Charge transport and film microstructure evolution are investigated in a series of polyethylenimine (PEI)-doped (0.0-6.0 wt%) amorphous metal oxide (MO) semiconductor thin film blends. Here, PEI doping generality is broadened from binary In2O3 to ternary (e.g., In+Zn in IZO, In+Ga in IGO) and quaternary (e.g., In+Zn+Ga in IGZO) systems, demonstrating the universality of this approach for polymer electron doping of MO matrices. Systematic comparison of the effects of various metal ions on the electronic transport and film microstructure of these blends are investigated by combined thin-film transistor (TFT) response, AFM, XPS, XRD, X-ray reflectivity, and cross-sectional TEM. Morphological analysis reveals that layered MO film microstructures predominate in PEI-In2O3, but become less distinct in IGO and are not detectable in IZO and IGZO. TFT charge transport measurements indicate a general coincidence of a peak in carrier mobility (μpeak) and overall TFT performance at optimal PEI doping concentrations. Optimal PEI loadings that yield μpeak values depend not only on the MO elemental composition but also, equally important, on the metal atomic ratios. By investigating the relationship between the MO energy levels and PEI doping by UPS, it is concluded that the efficiency of PEI electron-donation is highly dependent on the metal oxide matrix work function in cases where film morphology is optimal, as in the IGO compositions. The results of this investigation demonstrate the broad generality and efficacy of PEI electron doping applied to electronically functional metal oxide systems and that the resulting film microstructure, morphology, and energy level modifications are all vital to understanding charge transport in these amorphous oxide blends.
AB - Charge transport and film microstructure evolution are investigated in a series of polyethylenimine (PEI)-doped (0.0-6.0 wt%) amorphous metal oxide (MO) semiconductor thin film blends. Here, PEI doping generality is broadened from binary In2O3 to ternary (e.g., In+Zn in IZO, In+Ga in IGO) and quaternary (e.g., In+Zn+Ga in IGZO) systems, demonstrating the universality of this approach for polymer electron doping of MO matrices. Systematic comparison of the effects of various metal ions on the electronic transport and film microstructure of these blends are investigated by combined thin-film transistor (TFT) response, AFM, XPS, XRD, X-ray reflectivity, and cross-sectional TEM. Morphological analysis reveals that layered MO film microstructures predominate in PEI-In2O3, but become less distinct in IGO and are not detectable in IZO and IGZO. TFT charge transport measurements indicate a general coincidence of a peak in carrier mobility (μpeak) and overall TFT performance at optimal PEI doping concentrations. Optimal PEI loadings that yield μpeak values depend not only on the MO elemental composition but also, equally important, on the metal atomic ratios. By investigating the relationship between the MO energy levels and PEI doping by UPS, it is concluded that the efficiency of PEI electron-donation is highly dependent on the metal oxide matrix work function in cases where film morphology is optimal, as in the IGO compositions. The results of this investigation demonstrate the broad generality and efficacy of PEI electron doping applied to electronically functional metal oxide systems and that the resulting film microstructure, morphology, and energy level modifications are all vital to understanding charge transport in these amorphous oxide blends.
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U2 - 10.1021/jacs.8b01252
DO - 10.1021/jacs.8b01252
M3 - Article
C2 - 29617121
AN - SCOPUS:85045961138
SN - 0002-7863
VL - 140
SP - 5457
EP - 5473
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 16
ER -