Abstract
Charge transport measurements have been performed using the photo induced charge extraction by linearly increasing voltage (photo-CELIV) technique on indium tin oxide/titanium dioxide/ poly(3-hexylthiophene):[6,6]-phenyl C61 butyric acid methyl ester/copper (ITO/TiO2/P3HT:PCBM/Cu) devices. By adjusting the offset voltage such that holes are accumulated at the ITO/TiO2 contact we obtain space charge limited current (SCLC) extraction in the dark. Using photo-generation the current response is limited by SCLC extraction at low carrier concentrations but becomes purely recombination limited at high photo-generated carrier concentration. A 1-D drift diffusion model has been developed to simulate our results and we show that the hole blocking ITO/TiO2 contact is responsible for the SCLC behavior. The highly reduced recombination of charges seen in P3HT: PCBM devices is necessary to obtain the large extraction current transients that are seen in the experimental measurements. By comparing the simulated dark CELIV and photo-CELIV we show that photo-generated extraction is more sensitive towards changes in the surface recombination velocity. (C) 2014 Elsevier B.V. All rights reserved.
| Original language | Undefined/Unknown |
|---|---|
| Pages (from-to) | 3506–3513 |
| Number of pages | 8 |
| Journal | Organic Electronics |
| Volume | 15 |
| Issue number | 12 |
| DOIs | |
| Publication status | Published - 2014 |
| MoE publication type | A1 Journal article-refereed |
Keywords
- Blocking layer
- Bulk-hetero junction
- Charge transport
- Photo-CELIV
- TiO2