Self‐Assembled, Nanowire Network Electrodes for Depleted Bulk Heterojunction Solar Cells

Lan, Xinzheng; Bai, Jing; Masala, S.; Thon, Susanna M.; Ren, Yuan; Kramer, Illan J.; Hoogland, Sjoerd; Simchi, A.; Koleilat, Ghada I.; Paz-Soldan, Daniel; Ning, Zhijun; Labelle, André J.; Kim, Jin Young; Jabbour, Ghassan E.; Sargent, Edward H.

doi:10.1002/adma.201203759

Cited by 105 publications

(105 citation statements)

References 24 publications

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“…Of particular relevance among these features is the reduction of interdot distance to facilitate exciton dissociation and separate carrier transport towards the collecting contacts. Progress in the application of short organic ligands together with the use of QDs harvesting infrared photons were key advances leading to the 47% power conversion efficiency in CQD solar cells 4,6 .…”

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confidence: 99%

Selective contacts drive charge extraction in quantum dot solids via asymmetry in carrier transfer kinetics

et al. 2013

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Colloidal quantum dot solar cells achieve spectrally selective optical absorption in a thin layer of solution-processed, size-effect tuned, nanoparticles. The best devices built to date have relied heavily on drift-based transport due to the action of an electric field in a depletion region that extends throughout the thickness of the quantum dot layer. Here we study for the first time the behaviour of the best-performing class of colloidal quantum dot films in the absence of an electric field, by screening using an electrolyte. We find that the action of selective contacts on photovoltage sign and amplitude can be retained, implying that the contacts operate by kinetic preferences of charge transfer for either electrons or holes. We develop a theoretical model to explain these experimental findings. The work is the first to present a switch in the photovoltage in colloidal quantum dot solar cells by purposefully formed selective contacts, opening the way to new strategies in the engineering of colloidal quantum dot solar cells.

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confidence: 99%

Selective contacts drive charge extraction in quantum dot solids via asymmetry in carrier transfer kinetics

et al. 2013

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“…This has led to promising optoelectronic devices for lighting 3,4 , solar power conversion [5][6][7][8][9] and photon detection 10,11 . In solar cells, these materials have recently exceeded 7% certified power conversion efficiency (PCE) 5,12,13 , offering a promising path towards efficient, low-cost and roll-to-roll processed photovoltaics (PVs). Recent efforts have concentrated on eliminating trap states detrimental to carrier lifetime 5,14,15 , investigating the impact of size polydispersity on an ensemble of CQDs 16,17 , improving charge collection 13,18,19 , characterizing field-effect mobility in these materials [20][21][22][23] and developing novel doping strategies to enable new high-efficiency device architectures 6,[24][25][26] .…”

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Engineering colloidal quantum dot solids within and beyond the mobility-invariant regime

et al. 2014

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Colloidal quantum dots are attractive materials for efficient, low-cost and facile implementation of solution-processed optoelectronic devices. Despite impressive mobilities (1-30 cm 2 V À 1 s À 1 ) reported for new classes of quantum dot solids, it is-surprisingly-the much lower-mobility (10 À 3 -10 À 2 cm 2 V À 1 s À 1 ) solids that have produced the best photovoltaic performance. Here we show that it is not mobility, but instead the average spacing among recombination centres that governs the diffusion length of charges in today's quantum dot solids. In this regime, colloidal quantum dot films do not benefit from further improvements in charge carrier mobility. We develop a device model that accurately predicts the thickness dependence and diffusion length dependence of devices. Direct diffusion length measurements suggest the solid-state ligand exchange procedure as a potential origin of the detrimental recombination centres. We then present a novel avenue for in-solution passivation with tightly bound chlorothiols that retain passivation from solution to film, achieving an 8.5% power conversion efficiency.

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“…Additional advances in BH structures included the use of nanowires to increase the CQD film loading fraction [209,210]. Figure 3 illustrates a bottom-up fabrication technique that was used to realize nanowire network TiO 2 electrodes for a CQD BH solar cell.…”

Section: Depleted Heterojunction Cqd Photovoltaicsmentioning

confidence: 99%

Advancing colloidal quantum dot photovoltaic technology

et al. 2016

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Colloidal quantum dots (CQDs) are attractive materials for solar cells due to their low cost, ease of fabrication and spectral tunability. Progress in CQD photovoltaic technology over the past decade has resulted in power conversion efficiencies approaching 10%. In this review, we give an overview of this progress, and discuss limiting mechanisms and paths for future improvement in CQD solar cell technology. We briefly summarize nanoparticle synthesis and film processing methods and evaluate the optoelectronic properties of CQD films, including the crucial role that surface ligands play in materials performance. We give an overview of device architecture engineering in CQD solar cells. The compromise between carrier extraction and photon absorption in CQD photovoltaics is analyzed along with different strategies for overcoming this trade-off. We then focus on recent advances in absorption enhancement through innovative device design and the use of nanophotonics. Several light-trapping schemes, which have resulted in large increases in cell photocurrent, are described in detail. In particular, integrating plasmonic elements into CQD devices has emerged as a promising approach to enhance photon absorption through both near-field coupling and far-field scattering effects. We also discuss strategies for overcoming the single junction efficiency limits in CQD solar cells, including tandem architectures, multiple exciton generation and hybrid materials schemes. Finally, we offer a perspective on future directions for the field and the most promising paths for achieving higher device efficiencies.

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Self‐Assembled, Nanowire Network Electrodes for Depleted Bulk Heterojunction Solar Cells

Cited by 105 publications

References 24 publications

Selective contacts drive charge extraction in quantum dot solids via asymmetry in carrier transfer kinetics

Selective contacts drive charge extraction in quantum dot solids via asymmetry in carrier transfer kinetics

Engineering colloidal quantum dot solids within and beyond the mobility-invariant regime

Advancing colloidal quantum dot photovoltaic technology

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