Abstract
The temperature and photoexcitation density dependences of the electron transport dynamics in electrolyte-filled mesoporous TiO2 nanoparticle films were investigated by transient photocurrent measurements. The thermal activation energy of the diffusion coefficient of photogenerated electrons ranged from 0.19-0.27 eV, depending on the specific sample studied. The diffusion coefficient also depends strongly on the photoexcitation density; however, the activation energy has little, if any, dependence on the photoexcitation density. The light intensity dependence can be used to infer temperature-independent dispersion parameters in the range 0.3-0.5. These results are inconsistent with the widely used transport model that assumes multiple trapping of electrons in an exponential conduction-band tail. We can also exclude a model allowing for widening of a band tail with increased temperature. Our results suggest that structural, not energetic, disorder limits electron transport in mesoporous TiO2. The analogy between this material and others in which charge transport is limited by structural disorder is discussed.
| Original language | English (US) |
|---|---|
| Article number | 045326 |
| Journal | Physical Review B - Condensed Matter and Materials Physics |
| Volume | 73 |
| Issue number | 4 |
| DOIs | |
| State | Published - 2006 |
Fingerprint
ASJC Scopus subject areas
- Condensed Matter Physics
Cite this
Temperature dependence of the electron diffusion coefficient in electrolyte-filled TiO2 nanoparticle films : Evidence against multiple trapping in exponential conduction-band tails. / Kopidakis, Nikos; Benkstein, Kurt D.; Van De Lagemaat, Jao; Frank, Arthur J.; Yuan, Quan; Schiff, Eric Allan.
In: Physical Review B - Condensed Matter and Materials Physics, Vol. 73, No. 4, 045326, 2006.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Temperature dependence of the electron diffusion coefficient in electrolyte-filled TiO2 nanoparticle films
T2 - Evidence against multiple trapping in exponential conduction-band tails
AU - Kopidakis, Nikos
AU - Benkstein, Kurt D.
AU - Van De Lagemaat, Jao
AU - Frank, Arthur J.
AU - Yuan, Quan
AU - Schiff, Eric Allan
PY - 2006
Y1 - 2006
N2 - The temperature and photoexcitation density dependences of the electron transport dynamics in electrolyte-filled mesoporous TiO2 nanoparticle films were investigated by transient photocurrent measurements. The thermal activation energy of the diffusion coefficient of photogenerated electrons ranged from 0.19-0.27 eV, depending on the specific sample studied. The diffusion coefficient also depends strongly on the photoexcitation density; however, the activation energy has little, if any, dependence on the photoexcitation density. The light intensity dependence can be used to infer temperature-independent dispersion parameters in the range 0.3-0.5. These results are inconsistent with the widely used transport model that assumes multiple trapping of electrons in an exponential conduction-band tail. We can also exclude a model allowing for widening of a band tail with increased temperature. Our results suggest that structural, not energetic, disorder limits electron transport in mesoporous TiO2. The analogy between this material and others in which charge transport is limited by structural disorder is discussed.
AB - The temperature and photoexcitation density dependences of the electron transport dynamics in electrolyte-filled mesoporous TiO2 nanoparticle films were investigated by transient photocurrent measurements. The thermal activation energy of the diffusion coefficient of photogenerated electrons ranged from 0.19-0.27 eV, depending on the specific sample studied. The diffusion coefficient also depends strongly on the photoexcitation density; however, the activation energy has little, if any, dependence on the photoexcitation density. The light intensity dependence can be used to infer temperature-independent dispersion parameters in the range 0.3-0.5. These results are inconsistent with the widely used transport model that assumes multiple trapping of electrons in an exponential conduction-band tail. We can also exclude a model allowing for widening of a band tail with increased temperature. Our results suggest that structural, not energetic, disorder limits electron transport in mesoporous TiO2. The analogy between this material and others in which charge transport is limited by structural disorder is discussed.
UR - http://www.scopus.com/inward/record.url?scp=33144462564&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33144462564&partnerID=8YFLogxK
U2 - 10.1103/PhysRevB.73.045326
DO - 10.1103/PhysRevB.73.045326
M3 - Article
AN - SCOPUS:33144462564
VL - 73
JO - Physical Review B-Condensed Matter
JF - Physical Review B-Condensed Matter
SN - 0163-1829
IS - 4
M1 - 045326
ER -