Extremely long carrier lifetime at intermediate states in wall-inserted type II quantum dot absorbers

Sato, Daisuke; Ota, Junya; Nishikawa, Kaneyasu; Takeda, Yasuhiko; Miyashita, Naoya; Okada, Yoshitaka

doi:10.1063/1.4764030

Cited by 10 publications

(7 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, the physical behaviors such as confinement and absorption are very close in case of quantum dots. Moreover, if it is straigthforward to add a barrier between a QW and a contact, it is also feasible in case of quantum dots assuming a core-shell architecture [11] or dots embedded in specific material [12]. If in the present study we assume a QW, the conclusions can thus be easily extended to the quantum dots.…”

Section: Model and Systemmentioning

confidence: 93%

Beneficial impact of a thin tunnel barrier in quantum well intermediate-band solar cell

Cavassilas¹,

Suchet²,

Delamarre³

et al. 2018

EPJ Photovolt.

Self Cite

View full text Add to dashboard Cite

Using the non equilibrium Green functions formalism we propose a study of the electronic excitation and collection in nano-structured intermediate-band solar cell. We demonstrate that a thin tunnel barrier between the nano-objects and the host material is beneficial for both current and voltage. For the current, the confinement generated by such a thin barrier favors the intersubband optical coupling in the nano-objects and then improves the excitation-collection trade-off. We also show that a broaden density-of-state in the nano-objects increases the radiative recombination and then degrades the voltage. Using a detailed balance model we propose a broadening factor for this V oc degradation which decreases when a tunnel barrier enhances the life-time in the nano-objects.

show abstract

Section: Model and Systemmentioning

confidence: 93%

Beneficial impact of a thin tunnel barrier in quantum well intermediate-band solar cell

Cavassilas¹,

Suchet²,

Delamarre³

et al. 2018

EPJ Photovolt.

Self Cite

View full text Add to dashboard Cite

show abstract

“…We comment here on the origin of the blue-shift of the emission energy ∆E with increasing P in type II which we observe in our PL measurements. Currently, two competing hypotheses are put forward in this respect: the "state-filling" model, stemming from the observation of the large radiative lifetime of the emission from type-II QDs 15,28,[45][46][47] which occurs due to the smaller overlap between electron and hole wavefunctions 12,14 . If the pumping rate exceeds the emission rate of the ground state transition, which is often the case in type-II QDs, a larger proportion of the radiative transitions between electronic levels higher in energy than the ground state results.…”

Section: Model Of Blue-shiftmentioning

confidence: 99%

Excitonic structure and pumping power dependent emission blue-shift of type-II quantum dots

Klenovský

Steindl

Geffroy

2017

Sci Rep

View full text Add to dashboard Cite

In this work we study theoretically and experimentally the multi-particle structure of the so-called type-II quantum dots with spatially separated electrons and holes. Our calculations based on customarily developed full configuration interaction ap- proach reveal that exciton complexes containing holes interacting with two or more electrons exhibit fairly large antibinding energies. This effect is found to be the hallmark of the type-II confinement. In addition, an approximate self-consistent solution of the multi-exciton problem allows us to explain two pronounced phenomena: the blue-shift of the emission with pumping and the large inhomogeneous spectral broadening, both of those eluding explanation so far. The results are confirmed by detailed intensity and polarization resolved photoluminescence measurements on a number of type-II samples.

show abstract

“…When thin potential walls, through which holes generated in the QDs can escape into the matrix by tunneling, are inserted between the QDs and matrix, electrons and holes are farther separated, leading to less interaction between them [62,63]. Pandy et al designed CdSe/ZnS/ZnSe/CdSe concentric QDs with organic ligands on the QD surfaces to trap the holes [64].…”

Section: Quantum Dot Materials With Phonon-bottleneck Effectsmentioning

confidence: 98%

Requisites for Highly Efficient Hot-Carrier Solar Cells

Takeda

2013

Lecture Notes in Nanoscale Science and Technology

Self Cite

View full text Add to dashboard Cite

We have constructed new models based on detailed balance of particle and energy fluxes to clarify the operating principle of hot-carrier solar cells (HC-SCs) and find the requisites for high conversion efficiency. Energy dissipation due to thermalization of photogenerated carriers can be significantly reduced, even though the thermalization time is not sufficiently long. Instead, the energy dissipation related to entropy generation associated with hot-carrier extraction is remarkable. The thermalization time must be several nanoseconds to exceed the Shockley-Queisser limit under the 1 sun solar irradiation and over 10 ns to compete against triple-junction solar cells at 1,000 sun. The other requisites unique to hot-carrier extraction are a short carrier equilibration time being around one-thousandth of the thermalization time, and an energy-selection width of energy-selective contacts (ESCs) for mono-energetic carrier extraction, which is needed to match the quasi-Fermi levels in the hot absorber and in the cold electrodes, being narrower than 0.1 eV. It seems extremely challenging to fulfill all the requisites, although investigations for material development as well as new concepts for post conventional HC-SCs are underway. IntroductionIn a conventional solar cell, a photon whose energy is higher than the bandgap of the light-absorbing material used in the cell is absorbed to generate a carrier with an energy equal to the photon energy. However, carrier energies in excess of the bandgap of the absorber immediately dissipate by emitting phonons whose temperature equals the room temperature, namely, thermalization of carriers occurs within several picoseconds in most cases. Therefore, the excess carrier energies cannot be

show abstract

Extremely long carrier lifetime at intermediate states in wall-inserted type II quantum dot absorbers

Cited by 10 publications

References 27 publications

Beneficial impact of a thin tunnel barrier in quantum well intermediate-band solar cell

Beneficial impact of a thin tunnel barrier in quantum well intermediate-band solar cell

Excitonic structure and pumping power dependent emission blue-shift of type-II quantum dots

Requisites for Highly Efficient Hot-Carrier Solar Cells

Contact Info

Product

Resources

About