Related Experiment Video
Updated: Apr 21, 2026
11:26
Integrating a Triplet-triplet Annihilation Up-conversion System to Enhance Dye-sensitized Solar Cell Response to Sub-bandgap Light
Published on: September 12, 2014
13.2K
Ionic liquid dependence of triplet-sensitized photon upconversion
Yoichi Murakami1, Toshiyuki Ito, Akio Kawai
1Department of Mechanical Sciences and Engineering, Tokyo Institute of Technology , 2-12-1-I1-15 Ookayama, Meguro-ku, Tokyo 152-8552, Japan.
The Journal of Physical Chemistry. B
|November 11, 2014
Summary
Photon upconversion (UC) efficiently converts low-energy photons to higher energies using triplet-triplet annihilation. This study reveals that ionic liquid viscosity, not solvatochromic shifts, significantly impacts UC efficiency, guiding future improvements.
Area of Science:
- Photonic energy conversion
- Materials science
- Physical chemistry
Background:
- Photon upconversion (UC) technology converts lower-energy photons into higher-energy ones.
- Triplet-sensitized UC via triplet-triplet annihilation (TTA) is promising for noncoherent sunlight applications.
- Ionic liquids (ILs) offer nonvolatility and nonflammability advantages for UC media.
Purpose of the Study:
- To systematically investigate the influence of different ionic liquids (ILs) on triplet-sensitized photon upconversion efficiency (ΦUC).
- To identify key properties of ILs that correlate with UC performance.
- To provide guidelines for enhancing ΦUC in IL-based systems.
Main Methods:
- Fabrication and purification of samples using over 10 distinct ionic liquids.
- Systematic investigation of UC efficiency (ΦUC) across various ILs.
- Analysis of correlations between IL properties (viscosity, solvatochromic shifts) and ΦUC.
Main Results:
- UC efficiency (ΦUC) demonstrated clear dependencies on the specific ionic liquids used.
- A strong correlation was found between IL viscosity and UC efficiency.
- Solvatochromic shifts of the ILs did not show a significant correlation with UC efficiency trends.
Conclusions:
- The dynamic properties of ILs, particularly viscosity, play a crucial role in governing the kinetics of triplet-triplet annihilation upconversion.
- IL viscosity is a key factor for optimizing ΦUC, more so than electronic interactions indicated by solvatochromic shifts.
- These findings offer a pathway to rationally design and select ILs for improved photon upconversion performance.
Related Concept Videos
01:25Deactivation Processes: Jablonski Diagram
2.4K
Luminescence, the emission of light by a substance that has absorbed energy, is a process that involves the interaction of molecules with light. The energy-level diagram, or Jablonski diagram, is a graphical representation of these interactions, illustrating the various states and transitions a molecule can undergo. In a typical Jablonski diagram, the lowest horizontal line represents the ground-state energy of the molecule, which is usually a singlet state. This state represents the energies...
2.4K
01:26Photochemical Electrocyclic Reactions: Stereochemistry
2.5K
The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
Selection Rules: Photochemical Activation
2.5K
01:23Photoluminescence: Fluorescence and Phosphorescence
6.7K
Photoluminescence is a process where a molecule absorbs light energy and re-emits it in the form of light. This phenomenon occurs when a substance absorbs photons, promoting its electrons to higher energy level excited states, followed by a relaxation process in which the electrons return to their original ground state energy levels and emit light. Photoluminescence is widely observed in various materials, including semiconductors, and organic and inorganic compounds.
A pair of electrons in a...
A pair of electrons in a...
6.7K
01:14Photoluminescence: Applications
1.3K
Photoluminescence offers a wide range of applications due to its inherent sensitivity and selectivity. This technique allows for both direct and indirect analyses of the analyte. Direct quantitative analysis is possible when the analyte exhibits a favorable quantum yield for fluorescence or phosphorescence. However, an indirect analysis may be feasible if the analyte is not fluorescent or phosphorescent, or if the quantum yield is unfavorable. Indirect methods include reacting the analyte with...
1.3K
01:26Variables Affecting Phosphorescence and Fluorescence
3.8K
Fluorescence and phosphorescence are essential phenomena in fields like analytical chemistry, biological imaging, and materials science, where they detect molecular properties and visualize cellular structures. Understanding the variables that influence these luminescent behaviors is crucial for maximizing accuracy and efficiency in their applications. These variables can broadly be grouped into chemical structure, solvent properties, and external conditions, each playing a distinct role in...
3.8K
01:12Cycloaddition Reactions: MO Requirements for Photochemical Activation
2.9K
Some cycloaddition reactions are activated by heat, while others are initiated by light. For example, a [2 + 2] cycloaddition between two ethylene molecules occurs only in the presence of light. It is photochemically allowed but thermally forbidden.
2.9K