# Synthesis and Electrical Properties of a New Bipolar Material Using Spacer Moiety
## 4 Conclusions  
To realize an efficient deep-blue OLED device, a donor-spacer-acceptor-type of DTPCZ with bipolar characteristics was successfully synthesized; its characteristics were confirmed. Cz was used as the donor, a Tz moiety was introduced as the acceptor, and a \(p\)-xylene group was adopted as the spacer to control the twisted structure of the molecule, as well as the electron densities of the HOMO and LUMO levels. When DTPCZ was applied to the EL-doped device, a CE of 1.2 cd/A, an EQE of 2.3%, and a PE of 0.7 lm/W were achieved. Additionally, the CIE y-value was 0.06, which is near the 0.08 value specified for OLED televisions and required for the development of deep-blue device platforms. In the future, it will be possible to develop many bipolar derivatives by using the strategies proposed in this study for deep-blue material design. Furthermore, this molecular design approach is applicable to various fields, including organic semiconductors.  
The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app14093593/s1](https://www.mdpi.com/article/10.3390/app14093593/s1)]([https://www.mdpi.com/article/10.3390/app14093593/s1](https://www.mdpi.com/article/10.3390/app14093593/s1)), Table S1: Absorption frequencies and oscillator strengths calculated with TD-B3 LYP/6-311G(d) for the DTPCZ; Figure S1: Electron density distributions of molecular orbitals of DTPCZ (calculated using the B3 LYP/def2-TZVP method); Figure S2: Normalized UV-Vis absorption spectra of (a) DTPCZ and (b) poly DTPCZ according to different polarities of solvents at 0.5 wt%; Figure S3: Transient photoluminescence decay spectra of the solution (toluene) (IRF: instrument response function), range: 100 \(\upmu\)s; Figure S4: EL characteristics of devices using DTPCZ as an EML dopant: (a) power efficiency versus current density, and (b) external quantum efficiency versus current density; Figure S5: J-V characteristics of HOD and EOD of DTPCZ; Figure S6:  
Figure 7: EL characteristics of DTPCZ devices as emission layers (EMLs) with respect to the dopant concentration: (**a**) J-V-L curves, (**b**) luminance efficiency versus current density, (**c**) EL spectra doped devices, and (**d**) band diagram of the materials in OLED devices.  
EL characteristics of devices using poly DTPCZ as EMLs (5 wt% dopant): (a) band diagram of the solution process OLED device, (b) J-V curve, and (c) EL spectrum of the doped device of poly DTPCZ; Figure S7: 1H NMR spectra of compound (**1**) recorded in DMSO-d\({}_{6}\) (300 MHz); Figure S8: 1H NMR spectra of compound (**2**) recorded in DMSO-d\({}_{6}\) (300 MHz); Figure S9: 1H NMR spectra of DTPCZ recorded in CDCl\({}_{3}\) (400 MHz); Figure S10: 13C NMR spectra of DTPCZ recorded in CDCl\({}_{3}\) (100 MHz); Figure S11: 1H NMR spectra of compound (**3**) recorded in CDCl\({}_{3}\) (400 MHz); Figure S12: GPC traces of synthesized poly DTPCZ using THF as eluent.  
Conceptualization, S.J. and J.P.; methodology, H.K.; validation, H.L. and J.P.; formal analysis, K.L.; investigation, S.P. and H.K.; resources, J.P.; writing--original draft preparation, S.J., S.P. and J.P.; writing--review and editing, H.L., K.L. and J.P.; visualization, S.J., S.P. and H.K.; supervision, J.P.; project administration, J.P.; funding acquisition, J.P. All authors have read and agreed to the published version of the manuscript.  
Not applicable.  
Data are contained within the article and Supplementary Materials.  
The authors declare no conflicts of interest.