Electron Transport, Trapping and Recombination in Anodic TiO <sub>2</sub> Nanotube Arrays
Bibliographic record
Abstract
Anodically synthesized TiO2 nanotube arrays (TNTAs) constitute an exciting ordered large bandgap semiconductor nanoarchitecture for use as scaffolds and active layers for solutionprocessable devices including but not limited to, optoelectronic sensors, photovoltaics, photodetectors, photocatalysts and photoelectrochemical cells. Charge transport, trapping and recombination are key attributes of the material architecture that significantly influence the properties and performance of the resulting optoelectronic devices, thus motivating this review article. Since nanocrystalline mesoporous TiO2 films (np-TiO2) are actively researched for the same applications, in many cases, TNTAs and np-TiO2 are direct competitors and it is therefore meaningful to compare the optoelectronic properties of the two architectures head-to-head. In addition, there exists a whole host of TNTA-specific applications such as bottom-up fabricated photonic crystals, bulk heterojunction organic solar cells and metallodielectric metamaterials that leverage the ordered channel architecture. Recent studies have established the order of magnitude superior recombination lifetimes in sensitized TNTAs as compared to sensitized np-TiO2 as well as the salutary effect of lower structural disorder in TNTAs resulting in trap-free electron diffusion coefficients approaching those of single crystals and two orders of magnitude larger than np-TiO2. Photoconductivity measurements using bandgap illumination in both single nanotubes and nanotube ensembles have resulted in similar values of the mobility-lifetime product (10-5-10-4 cm2V-1), which are four to six orders of magnitude higher than in nanoparticle electrodes. At the same time, TiO2 nanotubes have a larger trap density and a greater average trap-depth than nanoparticulate Ti2 films, pointing to the importance of synthesis modification to improve material quality and post-synthesis techniques for trap passivation.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".