Multiple Exciton Generation in Quantum Dot Photovoltaics

Multiple exciton generation (MEG) in quantum dot (QD) photovoltaics offers a route to surpass the Shockley–Queisser limit by converting the excess energy of a single high-energy photon into more than one electron–hole pair. In colloidal QDs, quantum confinement enhances Coulomb interactions and can slow hot-carrier cooling, thereby increasing the probability of carrier–carrier collisions that produce additional excitons. Various material systems—lead chalcogenides, halide perovskites and doped or core–shell architectures—have been explored to tailor the energy thresholds and timescales of MEG. Critical challenges include competition with ultrafast Auger recombination, efficient extraction of multiple carriers and integration into device architectures. Recent advances in surface chemistry, heterostructure design and spin-exchange mechanisms have demonstrated internal quantum efficiencies above 100% in prototype solar cells, underscoring the global potential of QD-based MEG for next-generation photovoltaic technologies.

Research from Nature Portfolio

Recent studies have shown that manganese-doped PbSe/CdSe core–shell QDs exploit spin-exchange Coulomb interactions to overcome the limitations of phonon-assisted relaxation, delivering up to a threefold enhancement in multiexciton yield via subpicosecond spin-flip pathways. In halide perovskite solar cells, carrier multiplication thresholds close to twice the band gap have enabled unbiased internal quantum efficiencies exceeding 110%, with device redesigns revealing hidden MEG contributions suppressed by conventional architectures. Foundational work on formamidinium lead iodide nanocrystals has further demonstrated a phonon bottleneck that yields a 2.25Eg threshold and a 75% MEG efficiency slope, offering mechanistic insights into the inverse Auger process and guidance for tuning nanocrystal confinement.

Multiple Exciton Generation in Quantum Dot Photovoltaics publication trend

The graph below shows the total number of articles in multiple exciton generation in quantum dot photovoltaics across all publications each year (not limited to Nature Index journals).

Technical terms

Multiple exciton generation (MEG): A process in which absorption of a single photon with energy above a material’s threshold produces two or more bound electron–hole pairs.

Quantum dot (QD): A nanoscale semiconductor particle in which electrons and holes are confined in all three dimensions, leading to discrete energy levels.

Carrier multiplication (CM): The conversion of excess kinetic energy of a photoexcited carrier into additional free charge carriers.

Auger recombination: A non-radiative decay event where recombination energy is transferred to a third carrier, reducing multiexciton yield.

Band gap (Eg): The energy difference between valence and conduction bands of a semiconductor; MEG typically requires photon energies exceeding twice Eg.

Internal quantum efficiency (IQE): The fraction of absorbed photons that result in collected charge carriers within a photovoltaic device.

References

1. Spin-exchange carrier multiplication in manganese-doped colloidal quantum dots. Nature Materials (2023).
2. Inverted CdSe/PbSe Core/Shell Quantum Dots with Electrically Accessible Photocarriers. ACS Energy Letters (2025).
3. Carrier multiplication in perovskite solar cells with internal quantum efficiency exceeding 100%. Nature Communications (2023).
4. Emerging Active Materials for Solar Cells: Progress and Prospects. Advanced Electronic Materials (2024).
5. Low threshold and efficient multiple exciton generation in halide perovskite nanocrystals. Nature Communications (2018).
6. Multiple exciton generation in quantum dot-based solar cells. Nanophotonics (2017).