Photoconductivity of organic semiconductor polymers studied by time-resolved THz-TDS

Esentürk, Okan
Heilweil, Edwin J.
This study employs optical-pump terahertzprobe time-domain spectroscopy to measure relative carrier mobilities of semiconductor organic polymer films of poly-3-hexylthiophene (P3HT) and poly(2,5-bis(3-tetradecylthiophen-2-yi) thieno[3,2-b]thiophene) (PBTTT) polymers and these results directly correlate to recently reported electrical device mobility measurements.. An approximately four-fold increase in mobility of P3HT is observed with molecular weight increase from c.a. 18 kD to 150 kD where the intrinsic film mobility saturates for molecular weight > 70 kD. The decay dynamics studies of these polymers showed almost no dependence on the molecular weight of the polymer. The studies also showed an order of magnitude increase in mobility between as cast P3HT films and annealed PBTTT films supporting a strong conjugation length effect. We also measured the mobility dependence on the film quality that is affected by regularity of the polymer, dispersing solvent, electron acceptor traps, and other film growth related parameters relevant to device manufacturing.


Ultrafast Photoinduced Carrier Dynamics of Organic Semiconductors Measured by Time-Resolved Terahertz Spectroscopy
Esentürk, Okan; Lane, Paul A; Heilweil, Edwin J (null, 2010-01-01)
Intrinsic properties of organic semiconductors are investigated by Time-Resolved Terahertz Spectroscopy (TRTS) to assess their relative mobilities and efficiencies. Our results are well correlated with device measurements and show the effectiveness and advantages of using this non-contact optical technique to rapidly identify prospective materials. After a brief introduction of the TRTS technique, we summarize our results from relative mobility measurements of the organic semiconductor polymers poly(3-hexyl...
Melinger, Joseph S.; Lane, Paul; Esentürk, Okan; Heilweil, Edwin (2010-06-25)
We present a study of photo-induced carrier dynamics in organic thin films that contain zinc phthalocyanine (ZnPc) and buckminsterfullerene (C-60) investigated by ultrafast time resolved terahertz spectroscopy (TRTS). We compare two classes of films: 1) blend films of ZnPc and C-60 prepared by co-evaporation, and 2) superlattice films from alternating neat layers of ZnPc and C-60, where the individual layer varies in thickness between 2 nm and 40 nm. These films are model structures for the charge generatio...
Nanoscale Thermal Transport in Single, Bilayer Graphene, and Graphite
Gholivand, Hamed; Donmezer, Nazli (2016-10-12)
In this study, ab-initio calculations were performed to obtain phonon dispersions of single, bilayer graphene, and graphite structures. Using these dispersions single mode relaxation times, thermal conductivities, and mean free paths (MFPs) have been calculated. Finally, calculated variables were used to understand the effects of additional layers to thermophysical properties, phonon mode contributions to thermal conductivity, and the limits for ballistic-diffusive heat transfer of single, bilayer graphene,...
Terahertz mobility measurements on poly-3-hexylthiophene films: Device comparison, molecular weight, and film processing effects
Esentürk, Okan; Heilweil, Edwin J. (2008-01-15)
We directly compare relative carrier mobilities in semiconducting organic polymer films measured using noncontact optical pump terahertz (THz) probe spectroscopy to those reported in electrical device studies. Relative transient signal amplitude measurements of photoinjected carrier mobility as a function of poly-3-hexylthiophene (P3HT) molecular weight correlate directly with electrical device test values, indicating that the THz method shows promise as a rapid material screening approach. We also present ...
Broadband THz Modulators Based on Multilayer Graphene on PVC
KAYA, Emine; Kakenov, Nurbek; Kocabas, Coskun; Altan, Hakan; Esentürk, Okan (2016-09-30)
In this study we present the direct terahertz timedomain spectroscopic measurement of CVD-grown multilayer graphene (MLG) on PVC substrate with an electrically tunable Fermi level. In a configuration consisting MLG and injected organic dopant, the transmitted intensity loss of terahertz radiation was observed with an applied voltage between 0 and 3.5 V.We showed that MLG on PVC devices provided approximately 100 % modulation between 0.2 and 1.5 THz at preferentially low operation voltage of ca. 3V. The obse...
Citation Formats
O. Esentürk and E. J. Heilweil, “Photoconductivity of organic semiconductor polymers studied by time-resolved THz-TDS,” Cardiff, İngiltere, 2007, p. 670, Accessed: 00, 2021. [Online]. Available: