Week 8 Summary Flashcards
(20 cards)
What is the main problem with thin solar cells?
They don’t absorb enough light due to reduced path length for photons.
How does plasmonics help solar cell efficiency?
By enhancing absorption through scattering, field enhancement, and SPPs.
What are EQE and IQE in photovoltaics?
EQE = carriers per incident photon; IQE = carriers per absorbed photon.
Why embed nanoparticles in the active layer of solar cells?
To enhance the local electromagnetic field and improve absorption.
How do dielectric shells around nanoparticles help solar cells?
They prevent direct contact with the active layer, avoiding electrical interference.
What is the main mechanism of SPR-based sensing?
Coupling of light to propagating surface plasmon polaritons (SPPs) at a metal/dielectric interface.
What is the main mechanism of LSPR-based sensing?
Resonant excitation of localised surface plasmons in metal nanoparticles.
Which is more sensitive: SPR or LSPR?
SPR is more sensitive (Δn ~ 10⁻⁵ vs 10⁻³ for LSPR).
What is the formula for sensor Figure of Merit (FOM)?
FOM = (Δλ / Δn) / FWHM
Why are SPPs good for sensing?
They are highly sensitive to changes in refractive index at the surface.
Why do LSPRs work better for detecting small molecules?
They have more localised fields and shorter penetration depths.
How are plasmonic patches used in biosensing?
They enhance fluorescence when placed near fluorescent molecules.
What enhancement factor can plasmonic patches provide?
Up to ~100× fluorescence intensity.
What plasmonic property enables photothermal therapy?
Strong absorption leads to Ohmic heating, which kills cancer cells.
Why are gold nanorods/nanoshells useful in therapy?
Their shape allows tuning of resonance to biological transparency window (~800 nm).
What is combinational plasmonic therapy?
Using nanoparticles for both heat and drug delivery/activation at tumour sites.
Why use aluminium instead of gold for UV plasmonics?
Al has better performance in the UV due to lower losses.
What advantage does UV plasmonics have for biosensing?
Higher sensitivity to biomolecules like DNA which absorb in the UV.
What does increasing nanoparticle size generally do to the plasmonic resonance?
It red-shifts the resonance (moves to longer wavelength).
What property of plasmonics enables new optical technologies?
Enhanced scattering, field concentration, and refractive index sensitivity at nanoscale.
