Doping a semiconductor can extend the light absorption range, however, it usually introduces mid-gap states, reducing the charge carrier lifetime. This report shows that doping lanthanum dititinate (La2Ti2O7) with nitrogen extends the valence band edge by creating a continuum of dopant states, increasing the light absorption edge from 380 nm to 550 nm without adding mid-gap states. The dopant states are experimentally resolved in the excited state by correlating transient absorption spectroscopy with a supercontinuum probe and DFT prediction. The lack of mid-gap states is further confirmed by measuring the excited state lifetimes, which reveal the shifted band edge only increased carrier thermalization rates to the band edge and not interband charge recombination under both ultraviolet and visible excitation. Terahertz (time-domain) spectroscopy also reveals that the conduction mechanism remains unchanged after doping, suggesting the states are delocalized.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1039/c5cp05637c | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Triplet Exciton Sensitization of Silicon Mediated by Defect States in Hafnium Oxynitride.
Adv Mater
December 2024
Research Laboratory of Electronics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA.
Singlet exciton fission has the potential to increase the efficiency of crystalline silicon solar cells beyond the conventional single junction limit. Perhaps the largest obstacle to achieving this enhancement is uncertainty about energy coupling mechanisms at the interfaces between silicon and exciton fission materials such as tetracene. Here, the previously reported silicon-hafnium oxynitride-tetracene structure is studied and a combination of magnetic-field-dependent silicon photoluminescence measurements and density functional theory calculations is used to probe the influence of the interlayer composition on the triplet transfer process across the hafnium oxynitride interlayer.
View Article and Find Full Text PDFElectronic and magnetic properties of the HfO monolayer engineered by doping with transition metals and nonmetal atoms towards spintronic applications.
Nanoscale Adv
December 2024
Institute of Theoretical and Applied Research, Duy Tan University Ha Noi 100000 Vietnam
Article Synopsis
- Doping two-dimensional (2D) materials, like the HfO monolayer, with transition metals (Mn and Fe) and nonmetals (B and C) alters their electronic and magnetic properties, making them useful for spintronic applications.
- The pristine HfO monolayer is nonmagnetic with a large band gap, but doping introduces magnetism; Mn and Fe doping leads to total magnetic moments of 3.00 and 4.00, whereas B and C impact the system's electronic characteristics.
- Pairing transition metals with nonmetal elements results in a magnetic semiconductor nature; however, these paired systems have smaller magnetic moments compared to single dopants, signifying a complex relationship between doping
Defect engineering in organic semiconductor based metal-dielectric photonic crystals.
Sci Rep
November 2024
Department of Physics, The University of Vermont, Burlington, VT, 05405, USA.
We investigate the band structure of metal-dielectric photonic crystals comprising stacked organic semiconductor microcavities with silver metal mirrors incorporating crystal defects: individual unit cells with aperiodic dimensionality. Both transfer matrix simulation and experimental verification are performed to investigate the impact on the photonic band structure as a single cavity is varied in size. The resulting mid-gap defect states are shown to hybridize with a photonic band at certain resonant dimensions.
View Article and Find Full Text PDFDetecting near-infrared (NIR) light with high efficiency is crucial for photodetectors that are applied in optical communication systems. Si hyperdoped with deep-level impurities provides a monolithic platform for infrared optoelectronics with room-temperature operation at telecommunication wavelengths. In this work, we present strongly enhanced NIR absorption via the hybridization between plasmon resonance and mid-gap states in Au-hyperdoped Si layers, prepared by ion implantation and pulsed laser melting.
View Article and Find Full Text PDFTheoretical investigation of Cu/silicates deposited on rutile TiO as a photocatalyst.
Phys Chem Chem Phys
October 2024
Physics Department, Lancaster University, Lancaster LA1 4YB, UK.
Article Synopsis
- Titanium dioxide (TiO) is a compound with unique optical properties, commonly used in photocatalysis, and recent studies suggest that incorporating Cu atomic quantum clusters (AQCs) can improve its efficiency.
- This research investigates how Cu interacts with both perfect and reduced TiO surfaces in the presence of silicate SiO ions, aimed at purifying the Cu AQCs while maintaining the compound's electronic properties.
- The results indicate that SiO enhances the electronic states within the band gap of the Cu@TiO composite and that oxygen vacancies, alongside Cu, contribute to improved photocatalytic performance by shifting electronic states.
Want AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!