Luminescent Down-Shifting Techniques in Photovoltaic Devices

Luminescent down-shifting (LDS) techniques employ luminescent materials to absorb high-energy (ultraviolet or blue) photons and re-emit them at longer wavelengths that better match the spectral response of photovoltaic absorbers. By integrating down-converting layers onto silicon or thin-film solar cells, researchers have addressed inherent spectral mismatch and surface recombination losses, improving external quantum efficiency (EQE) and overall power conversion efficiency (PCE). Materials under investigation include colloidal quantum dots, perovskite nanocrystals, organic molecular complexes and hybrid nanocomposites, each offering distinct advantages in absorption bandwidth, photoluminescence quantum yield (PLQY) and Stokes shift. Strategies encompass surface passivation to reduce non-radiative losses, encapsulation for environmental stability and incorporation of anti-reflection architectures. Recent efforts focus on enhancing device durability, optimising layer thickness, and exploiting resonant energy transfer to maximise carrier injection. The global pursuit of cost-effective, scalable LDS layers aims to extend modules’ spectral harvesting into the ultraviolet while preserving visible-region performance, thereby contributing to more efficient and sustainable solar technologies.

Research from Nature Portfolio

Recent studies have demonstrated the potential of molecular phosphorescent complexes as energy down-shifting layers on silicon nanowire solar cells. Highly engineered Ir(III) complexes featuring large Stokes shifts and long exciton diffusion lengths were deposited via ultrasonic spray, yielding crystalline films with exceptional PLQY. These layers effectively convert sub-450 nm photons to longer wavelengths, thereby diminishing surface recombination at nanowire facets. The optimised coatings increased internal quantum efficiency in the ultraviolet region and raised short-circuit current density by over 6%, illustrating the efficacy of molecular LDS converters in addressing intrinsic losses in nanostructured photovoltaic architectures.

Luminescent Down-Shifting Techniques in Photovoltaic Devices publication trend

The graph below shows the total number of articles in luminescent down-shifting techniques in photovoltaic devices across all publications each year (not limited to Nature Index journals).

Technical terms

Luminescent down-shifting (LDS): conversion of high-energy photons into lower-energy photons via luminescent materials to improve solar spectrum utilisation.

Quantum dot (QD): semiconductor nanocrystal exhibiting size-tunable optical absorption and emission with high photoluminescence quantum yield.

Photoluminescence quantum yield (PLQY): ratio of emitted to absorbed photons, indicating luminescent conversion efficiency.

External quantum efficiency (EQE): fraction of incident photons converted into collected charge carriers in a photovoltaic device.

Resonant energy transfer (RET): non-radiative transfer of excitation energy between donor and acceptor species in close proximity, enhancing carrier injection.

References

1. Phosphorescent Energy Downshifting for Diminishing Surface Recombination in Silicon Nanowire Solar Cells. Scientific Reports (2018).
2. Recent Advances in Colloidal Quantum Dots or Perovskite Quantum Dots as a Luminescent Downshifting Layer Embedded on Solar Cells. Nanomaterials (2022).
3. Parylene-Sealed Perovskite Nanocrystals Down-Shifting Layer for Luminescent Spectral Matching in Thin Film Photovoltaics. Nanomaterials (2023).
4. Efficient light harvesting in hybrid quantum dot–interdigitated back contact solar cells via resonant energy transfer and luminescent downshifting. Nanoscale (2019).