Charge-extraction strategies for colloidal quantum dot photovoltaics

Lan, Xinzheng; Masala, S.; Sargent, Edward H.

doi:10.1038/nmat3816

Cited by 277 publications

(229 citation statements)

References 80 publications

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“…58,59 Comparative studies on the use of organic and inorganic charge acceptor materials for PbS NCs have also been carried out. [60][61][62] Photoconductor devices fabricated via photosensitizing one dimensional (1D) nanomaterials with PbS NCs, including carbon nanotubes (CNTs) [63][64][65] and fullerene C60 nanorods, 53 benefit from the large donor/acceptor interface and also via harnessing plasmonic effects have been demonstrated. 66,67 PbS NC phototransistor devices.…”

Section: Restricting Attention To Recombination Centersmentioning

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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Section: Restricting Attention To Recombination Centersmentioning

confidence: 99%

Lead sulphide nanocrystal photodetector technologies

2016

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“…Both an efficient harvest of multi-exciton states and long optical path lengths for absorbing solar photons are possible. Part B is taken from [133].…”

Section: Discussionmentioning

confidence: 99%

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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“…The TiO 2 layer should be modified with an inorganic halide ligand, such as tetrabutylammonium iodide (TBAI), which Bawedi [73] utilized to create the bandgap offset ideal for charge separation, or one of the other commonly utilized ligands to manipulate the quantum dot band structure [75][76][77]. The TiO 2 layer should then be decorated with a largesize quantum dot capped with the same inorganic halide and then with a slightly smaller quantum dot capped with a thiol, such as thioglycolic acid or 1,2-ethanedithiol (EDT), to further encourage charge separation through bandgap modulation, utilizing the well-known bandgap modulation through size adjustment [78,79] and the added benefit that larger sized quantum dots have fewer accessible trap sites [80]. An interfacial layer, Au islands or conformal indium-tin oxide film, separates the two cells.…”

Section: Conclusion and Future Prospectsmentioning

confidence: 99%