Diffusion-Controlled Synthesis of PbS and PbSe Quantum Dots with <i>in Situ</i> Halide Passivation for Quantum Dot Solar Cells

Zhang, Jianbing; Gao, Jianbo; Miller, Elisa M.; Luther, Joseph M.; Beard, Matthew C.

doi:10.1021/nn405236k

Cited by 278 publications

(362 citation statements)

References 39 publications

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“…These approaches can be classified by synthesis strategy (e.g., hot injection, 11,12 heat-up, 13 or continuous flow 14 ) and precursor chemistry (e.g., PbO and bis(trimethylsilyl)sulfide (TMS-S), 11,14,15 PbO and substituted thioureas, 16 lead acetate (PbAc) and TMS-S, 17,18 PbCl 2 and elemental sulfur, 19,20 PbCl 2…”

Section: Introductionmentioning

confidence: 99%

Synthesis cost dictates the commercial viability of lead sulfide and perovskite quantum dot photovoltaics

Jean

Xiao

Nick

et al. 2018

Energy Environ. Sci.

123

113

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Any new solar photovoltaic (PV) technology must reach low production costs to compete with today's marketleading crystalline silicon and commercial thin-film PV technologies. Colloidal quantum dots (QDs) could open up new applications by enabling lightweight and flexible PV modules. However, the cost of synthesizing nanocrystals at the large scale needed for PV module production has not previously been investigated. Based on our experience with commercial QD scale-up, we develop a Monte Carlo model to analyze the cost of synthesizing lead sulfide and metal halide perovskite QDs using 8 different reported synthetic methods. We also analyze the cost of solution-phase ligand exchange for preparing deposition-ready PbS QD inks, as well as the manufacturing cost for roll-to-roll solution-processed PV modules using these materials. We find that present QD synthesis costs are prohibitively high for PV applications, with median costs of 11 to 59 $ per g for PbS QDs (0.15 to 0.84 $ per W for a 20% efficient cell) and 73 $ per g for CsPbI 3 QDs (0.74 $ per W). QD ink preparation adds 6.3 $ per g (0.09 $ per W). In total, QD materials contribute up to 55% of the total module cost, making even roll-to-roll-processed QDPV modules significantly more expensive than silicon PV modules. These results suggest that the development of new low-cost synthetic methods is critically important for the commercial relevance of QD photovoltaics. Using our cost model, we identify strategies for reducing synthetic cost and propose a cost target of 5 $ per g to move QD solar cells closer to commercial viability. Broader contextColloidal quantum dots (QDs) have been widely investigated as an avenue toward ultra-low-cost solar photovoltaics (PV), alongside organics and metal halide perovskites. It is often implicitly assumed-and explicitly stated-that QD-based PV technologies can reach low cost because they employ low-cost, abundant elements and low-temperature, high-throughput manufacturing processes. However, this argument holds true only if QDs can be synthesized at low cost-materials dictate the module cost floor. Here we report the first detailed analysis of the cost of large-scale QD synthesis for PV applications. Our Monte Carlo approach constitutes a complete cost modeling framework for QD photovoltaics, from raw precursors to finished modules. We find that QD synthesis is prohibitively expensive today, highlighting the importance of synthetic cost for the commercial viability of QD solar technologies and guiding further research toward promising synthetic directions.

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Section: Introductionmentioning

confidence: 99%

Synthesis cost dictates the commercial viability of lead sulfide and perovskite quantum dot photovoltaics

Jean

Xiao

Nick

et al. 2018

Energy Environ. Sci.

123

113

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“…Nevertheless surprisingly high mobilities were reported lately by several groups, [12][13][14][15][16][17][18] in high quality films made of different materials, suggesting that band-like transport through extended states is indeed achievable in CQD arrays, provided the surface traps are effectively passivated [18][19][20][21][22][23][24][25] and the separation between dots is reduced sufficiently by the use of extremely short ligands or inorganic capping. 26 This hypothesis is supported by the observed temperature dependence of mobility and conductivity [12][13][14][15][16][17][18] whereas the spectral broadening and red shifts of the 1S exciton peak observed in these systems, 13,27 may be indicative of strong electronic coupling between QDs, as are the remarkable values of diffusion lengths and lifetimes of charge carriers measured in QD solids.…”

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confidence: 99%

High-Mobility Toolkit for Quantum Dot Films

2016

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Semiconductor colloidal quantum dots (CQDs) are being increasingly exploited in electronics, optoelectronics and solar energy harvesting, using a variety of different architectures, mostly based on ordered 2D or 3D arrays of these nanostructures.A crucial issue for optimising the performance of such devices is the ability to predict and tune the transport properties of these assemblies. In this work we provide general guidelines to precisely that effect, indicating specific materials, crystal structures, lattice arrangements, surface stoichiometries and morphologies which favour high electron mobilities in these systems, and, conversely, materials that will exhibit low mobilities if nanostructured. At the same time our results evidence a surprising independence of the film's transport properties from those of the bulk material from which the dots are made, highlighting the crucial role of theoretical modelling to guide device design. Keywords: transport, nanocrystal quantum dots, films, dot arrays, pseudopotential methodColloidal quantum dots (CQDs) are attractive material systems characterized by outstanding properties, such as low manufacturing costs, high degree of uniformity and flexibility achieved in their synthesis, size-tunability of their electronic and optical properties, and even the ability to engineer their wave functions, enabling unprecedented control of the carriers' localization, that make them potentially ideally suited for a wide range of technological applications. Nevertheless the performance of CQD-based electronic and optoelectronic devices is still far from optimal, owing mainly to the poor transport properties displayed by their building blocks when arranged in arrays. The presence of countless interfaces, with associated traps 1 and potential steps, that the charge carriers need to cross in order to reach the electrodes where they can be collected, appears a daunting obstacle to efficient transport in these devices. Indeed measurements on early devices seemed to confirm this bleak scenario, and very low mobilities (of the order of 10 −2 cm 2 V −1 s −1 or less) were reported in CQD films. 2-5 These findings were supported by

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“…However, (TMS) 2 S and (TMS) 2 Se are flammable and toxic, and they readily hydrolyze with water to form toxic H 2 S and H 2 Se. This has led to the development of methods based on alternative precursors, including lead(II) chloride instead of PbO as the lead precursor to improve the surface passivation of the resulting CQDs [68,72], and elemental sulfur instead of (TMS) 2 S [73,74]. Additional novel growth methods have been proposed, including the synthesis of PbSe in a phosphate glass host [75].…”

Section: Synthesis Methodsmentioning

confidence: 99%

“…Studies have shown that device air stability and efficiency are greatly increased when the CQD active material is treated with Cl-containing ligands [16,72]. Several specific methods have been developed that take advantage of the properties of halogen ligands.…”

Section: Ligand Typesmentioning

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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Diffusion-Controlled Synthesis of PbS and PbSe Quantum Dots with in Situ Halide Passivation for Quantum Dot Solar Cells

Cited by 278 publications

References 39 publications

Synthesis cost dictates the commercial viability of lead sulfide and perovskite quantum dot photovoltaics

Synthesis cost dictates the commercial viability of lead sulfide and perovskite quantum dot photovoltaics

High-Mobility Toolkit for Quantum Dot Films

Advancing colloidal quantum dot photovoltaic technology

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