High charge-carrier mobility enables exploitation of carrier multiplication in quantum-dot films

Sandeep, C. S. Suchand; Cate, Sybren ten; Schins, Juleon M.; Savenije, Tom J.; Liu, Yao; Law, Matt; Kinge, Sachin; Houtepen, Arjan J.; Siebbeles, Laurens D. A.

doi:10.1038/ncomms3360

Cited by 75 publications

(104 citation statements)

References 38 publications

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“…Interestingly, PbSe nanorods in the solid state show a sharper increase in QY with photon energy compared to equivalent nanorods in solution despite the fact that device IQEs are typically reduced by Auger recombination competing with charge separation and by regular device recombination losses (see Figure 5). Similar observations have been reported for spherical QDs where the MEG yield of particles in film and solution have been examined via microwave conductivity measurements [117]. Possible explanations for this phenomenon range from the formation of interparticle QD band structures in the solid state [117] to potential trap-assisted MEG mechanisms [118].…”

Section: Tuning the Shape Of The Qdsupporting

confidence: 56%

“…Similar observations have been reported for spherical QDs where the MEG yield of particles in film and solution have been examined via microwave conductivity measurements [117]. Possible explanations for this phenomenon range from the formation of interparticle QD band structures in the solid state [117] to potential trap-assisted MEG mechanisms [118].…”

Section: Tuning the Shape Of The Qdsupporting

confidence: 56%

“…Auger recombination), which is governed by the same matrix element, no difference in recombination timescales as a function of apparent quantum confinement has been found in the series PbS, PbSe and PbTe [31,69]. Considering ultra-fast exciton separation close to QD-MO interfaces (see Section 3.1) [110] and material independent Auger kinetics, it is conceivable that the higher MEG yields for heavy lead chalcogenide QD devices is due [26,27,46,117].…”

Section: The Choice Of Qd Materialsmentioning

confidence: 99%

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Multiple exciton generation in quantum dot-based solar cells

et al. 2017

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Multiple exciton generation (MEG) in quantumconfined semiconductors is the process by which multiple bound charge-carrier pairs are generated after absorption of a single high-energy photon. Such charge-carrier multiplication effects have been highlighted as particularly beneficial for solar cells where they have the potential to increase the photocurrent significantly. Indeed, recent research efforts have proved that more than one chargecarrier pair per incident solar photon can be extracted in photovoltaic devices incorporating quantum-confined semiconductors. While these proof-of-concept applications underline the potential of MEG in solar cells, the impact of the carrier multiplication effect on the device performance remains rather low. This review covers recent advancements in the understanding and application of MEG as a photocurrent-enhancing mechanism in quantum dot-based photovoltaics.

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Section: Tuning the Shape Of The Qdsupporting

confidence: 56%

Section: Tuning the Shape Of The Qdsupporting

confidence: 56%

Section: The Choice Of Qd Materialsmentioning

confidence: 99%

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Multiple exciton generation in quantum dot-based solar cells

et al. 2017

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“…. 93 With both ptype and n-type PbS NC availability along with their tunable bandgap, there remains an intresting opportunity to realise all PbS p-n heterojunction photodiodes.…”

Section: Discussionmentioning

confidence: 99%

Lead sulphide nanocrystal photodetector technologies

2016

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2 Few other areas of study have uncovered the secrets of the universe like that of the interaction between light and matter, leading to many revolutionary scientific discoveries. The interaction of light, in particular with semiconducting materials, has enabled us to understand the behaviour of various fundamental phenomena and has laid the foundation of the optoelectronic systems that we rely on today. The majority of such systems necessitate the detection of light which is achieved via the use of photodetector devices. A photodetector converts incident photons into an electrical signal, which in the solid-state, is assembled together with an application-oriented readout integrated circuit (ROIC). Present-day commercially available photodetectors are typically made from gallium phosphide/silicon carbide (GaP)/(SiC), silicon (Si) and indium gallium arsenide/germanium (InGaAs)/(Ge) for detection in the ultraviolet (UV), visible and near-infrared (IR) regimes of the electromagnetic spectrum, respectively. For mid and far IR, lead sulphide (PbS), lead selenide (PbSe), indium antimonide (InSb), indium arsenide (InAs) and mercury cadmium telluride (HgCdTe) based photodetectors are commonly used. Photodetectors based on a photoemissive principle such as photomultiplier tubes (PMTs) are also widely used for ultrasensitive detection in the UV to near-IR spectral regime and are fabricated using alkali metals having a low workfunction. For applications demanding multispectral detection, 'two-colour' detectors are often manufactured with a bi-level structure, for example consisting of an IR transmitting Si photodiode mounted over an IR sensitive PbS photoconductor. Such a device structure has drawbacks that include added cost, increased complexity of device fabrication and associated issues in implementation. Furthermore, a significant majority of applications are based upon UV to near-IR light detection where the indirect bandgap of Si, the InGaAs epitaxial growth process, PMT bulkiness and high bias voltage requirement all present challenges and renders their use with flexible platforms impossible. As a result significant research effort continues to be expended on the development of a singlesystem multispectral photodetector to replace two or more detectors. In the last decade amongst all the candidate materials studied 1 PbS semiconductor nanocrystals (NCs), often referred as 'quantum dots', have emerged as the most promising material for the fabrication of 3 this type of photodetector. Such has been the progress in their development that reported PbS NC based photodetectors have already outperformed conventional state-of-the-art photodetectors in many aspects including low-cost room temperature device fabrication via solution processing, flexible substrate compatibility, broadband spectral sensitivity along with the figures of merit achieved, Fig 1a. In this review article, we present an overview of recent developments in PbS NC based photodetectors. We first provide a brief introduction to PbS NCs and their releva...

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“…2) and EQE spectra (Fig. 1d) that do not show red-shift and broadening as signatures of increased electronic coupling and loss of quantum confinement 26,27 . This is in agreement with a previous report by Gao et al 28 , in which annealing of EDT-treated PbS films was reported to suppress deep traps in the temperature regime investigated herein without loss of quantum confinement.…”

Section: Oh -Suppression and Improved Passivation Via Thermal Annealingmentioning

confidence: 99%

The role of surface passivation for efficient and photostable PbS quantum dot solar cells

et al. 2016

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For any emerging photovoltaic technology to become commercially relevant, both its power conversion efficiency and photostability are key parameters to be fulfilled. Colloidal quantum dot solar cells are a solution-processed, low-cost technology that has reached efficiency about 9% by judiciously controlling the surface of the quantum dots to enable surface passivation and tune energy levels. However, the role of quantum dot's surface on the stability of these solar cells has remained elusive. Here we report on highly efficient and photostable quantum dot solar cells with efficiencies of 9.6% (and independently certificated values of 8.7%). As a result of optimised surface passivation and suppression of hydroxyl ligands-which are found to be detrimental for both efficiency and photostability-the efficiency remains within 80% after

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High charge-carrier mobility enables exploitation of carrier multiplication in quantum-dot films

Cited by 75 publications

References 38 publications

Multiple exciton generation in quantum dot-based solar cells

Multiple exciton generation in quantum dot-based solar cells

Lead sulphide nanocrystal photodetector technologies

The role of surface passivation for efficient and photostable PbS quantum dot solar cells

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