# Presentation: 871613

## Development of the single-crystal organic field-effect transistors (OFETs) at Rutgers enabled the exploration of transport phenomena in organic semiconductors and the fundamentals of organic electronics. The main results of the 2nd year of the project:

**  ****the first real space molecular resolution images of the surface  of a single crystal organic semiconductor**
- E. Menard et al., *Adv. Mater.* **18**, 1552-1556 (2006)
**  ****observation of the Hall effect in OFETs; ****first direct measurements of the density of mobile field-induced carriers in the OFET channel **
- V. Podzorov et al., *Phys. Rev. Lett*. 95, 226601 (2005).** **
**  ****the first review on the fundamentals of charge transport in single-crystal organic transistors**** **
** **
- M. E. Gershenson et al., *Rev. Mod. Phys*., Sept. 2006
** ****fast carrier** **dynamics of light-induced excitations in organic crystals**** **
** **
- H. Najafov et al., *Phys. Rev. Lett. ***96**, 056604 (2006)
- O.** **Ostroverkhova et al., *Appl. Phys. Lett*. **88**, 162101 (2006).
**  ****ultrasensitive sensing with organic field-effect transistors**** **
- V. Podzorov et al., *Appl. Phys. Lett*. **87**, 093505 (2005).
**  ****observation of the p****hoto-induced charge transfer at the interface between organic molecular crystals and polymers**** **
- V. Podzorov and M. E. Gershenson,, *Phys. Rev. Lett*. **95**, 016602 (2005).

**“****air-gap” organic single-crystal field-effect transistor**

**Notes:**
The on-going NSF-funded research focuses on exploration of the fundamental electronic processes in organic semiconductors that determine operation and ultimate performance of devices of organic electronics. We have introduced several novel designs of the single-crystal OFETs, including the so-called “air-gap” devices that completely eliminate any contact between an organic surface and a solid gate dielectric. When combined with high-quality organic crystals, this design reveals the ultimate OFET performance, determined solely by the intrinsic (not limited by disorder) polaronic transport on the pristine surface of the crystals. These transistors with the fully accessible conducting channel provide a unique tool to study the interactions between organic surfaces and active species in the environment. 
Our results on the structure of the surfaces of molecular crystals, mechanisms of formation of electronic defects on these surfaces, and photo-induced processes on the interface between organic semiconductors and gate insulators have an important impact on foundations of the emerging field of ‘flexible’ electronics. The study of single-crystal organic transistors has already resulted in a significant increase of the carrier mobility in this important class of devices. Development of the organic transistors with the fully accessible conducting channel is an important step towards better organic sensors. 

## Education:

**Res. Assoc. and co-PI:**** Vitaly Podzorov**
**Undergrad. students:****  Matt ****Calhoun****  and Javier Sanchez**
**Collaborators:**
** ****I. Biaggio, H. Najafov (Lehigh U.) **
** ****D. Frisbie ****(U. Minnesota)**
** ****J. Rogers,**** ****E. Menard ****(UIUC)**
** ****A. Morpurgo**** (Delft Tech. U.)**
** ****D. Fichou (CEA-Saclay)**
** ****O. Ostroverkhova, F. Hegmann (U. Alberta)**
** ****J. Anthony (U. Kentucky)**

**Our results have been recognized by Scientific American as one of the major contribution to the development of flexible electronics in 2005. **_[Scientific American 50 Award](http://www.sciamdigital.com/browse.cfm?ITEMIDCHAR=5D19F351-2B35-221B-6264C230B770D005&methodnameCHAR=&interfacenameCHAR=browse.cfm&ISSUEID_CHAR=5CE65F08-2B35-221B-6CA922740414072A&ArticleTypeSubInclude_BIT=0&sequencenameCHAR=itemP)__,_*** Scientific American, Dec. 2005.***

**MG and VP were co-organizers of the ICAM Workshop on Electronic Phenomena in Single-Crystal Organic Semiconductors, ****Baltimore, March, 2006, which attracted ~ 40 leading researchers from the USA, Japan, France, Italy, the Netherlands, Great Britain, and Switzerland. **_[http://www.physics.rutgers.edu/ICAM-EPOS](http://www.physics.rutgers.edu/ICAM-EPOS)_

**single-crystal rubrene OFET**