PHOTO-CARRIER DYNAMICS OF BLENDED AND MULTI-LAYERED FILMS OF ZINC PHTHALOCYANINE AND C-60 MEASURED BY TIME-RESOLVED TERAHERTZ SPECTROSCOPY

Date

2010-06-25

Author

Melinger, Joseph S.
Lane, Paul
Esentürk, Okan
Heilweil, Edwin

Metadata

Show full item record

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Item Usage Stats

66
views

0
downloads

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 generation layers in organic photovoltaics, and their photo-carrier dynamics on a femtosecond to nanosecond timescale is of high interest. Using TRTS, which employs an optical pump pulse and a time delayed terahertz (THz) probe pulse, we find evidence for a short-lived charge transfer state of C-60 that decays within several picoseconds of excitation. Both blend and superlattice films have a long-lived (> 80 picoseconds) THz absorption that is dependent on the structure and composition of the films. The optimum composition for maximum photocarrier generation efficiency is a 1:1 blend of ZnPc and C-60. Amongst the layered films, we find that the photocarrier efficiency increases as the individual layer thickness decreases, with the film having ultrathin alternating 2 nm thick layers exhibiting the strongest THz absorption. A much stronger THz absorption signal was obtained for the 2 nm layered film than for the best blend film.

Subject Keywords

Charge exchange, Fullerenes, Optical pumping, Organic semiconductors, Semiconductor superlattices, Semiconductor thin films, Solar cells, Terahertz spectroscopy, Vacuum deposition, Zinc compounds

URI

https://hdl.handle.net/11511/41313

DOI

https://doi.org/10.1109/pvsc.2010.5616508

Collections

Department of Chemistry, Conference / Seminar

Suggestions

OpenMETU
Core

Photoconductivity of organic semiconductor polymers studied by time-resolved THz-TDS Esentürk, Okan; Heilweil, Edwin J. (null; 2007-12-01) 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 ...
Photoexcitation Dynamics in Films of C-60 and Zn Phthalocyanine with a Layered Nanostructure Lane, Paul A.; Cunningham, Paul D.; Melinger, Joseph S.; Kushto, Gary P.; Esentürk, Okan; Heilweil, Edwin J. (2012-02-15) We elucidate photoexcitation dynamics in C-60 and zinc phthalocyanine (ZnPc) from picoseconds to milliseconds by transient absorption and time-resolved terahertz spectroscopy. Autoionization of C-60 is a precursor to photocarrier generation. Decay of the terahertz signal is due to decreasing photocarrier mobility over the first 20 ps and thereafter reflects recombination dynamics. Singlet diffusion rates in C-60 are determined by modeling the rise of ground state bleaching of ZnPc absorption following C-60 ...
Carrier dynamics of composite and nanolayered films of zinc phthalocyanine and C-60 measured by time-resolved terahertz spectroscopy Lane, Paul A.; Melinger, Joseph S.; Esentürk, Okan; Heilweil, Edwin J. (2009-08-06) We present a study of charge transfer and carrier dynamics in films of zinc phthalocyanine (ZnPc) and buckmisnsterfullerene (C-60) investigated by time-resolved terahertz spectroscopy (TRTS). These films are model structures for charge generation layers in organic photovoltaics and their intrinsic properties are therefore of interest. We compare two classes of films: composite films of ZnPc and C-60 prepared by co-evaporation and layered ZnPc/C-60 films prepared by alternating deposition. We find evidence f...
Photon-to-carrier efficiencies of nanostructured zinc-phthalocyanine/fullerene thin films assessed by time-resolved terahertz spectroscopy Esentürk, Okan; Lane, Paul A.; Heilweil, Edwin J. (null; 2008-01-01) Blend and multilayer Zinc-phthalocyanine/fullerene thin films were investigated as model active layers for solar cells by Time-Resolved Terahertz Spectroscopy. A strong dependence on the blend ratio and multilayer nano-structure of the films was found
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...

Citation Formats

J. S. Melinger, P. Lane, O. Esentürk, and E. Heilweil, “PHOTO-CARRIER DYNAMICS OF BLENDED AND MULTI-LAYERED FILMS OF ZINC PHTHALOCYANINE AND C-60 MEASURED BY TIME-RESOLVED TERAHERTZ SPECTROSCOPY,” 2010, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/41313.