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PbS Quantum Dots as Additives in Methylammonium Halide Perovskite Solar Cells: the Effect of Quantum Dot Capping
摘要： Colloidal PbS quantum dots (QDs) have been successfully employed as additives in Halide Perovskite Solar Cells (PSCs) acting as nucleation centers in the perovskite crystallization process. For this strategy, the surface functionalization of the QD, controlled via the use of different capping ligands, is likely of key importance. In this work, we examine the influence of the PbS QD capping on the photovoltaic performance of methylammonium lead iodide PSCs. We test PSCs fabricated with PbS QD additives with different capping ligands including methylammonium lead iodide (MAPI), cesium lead iodide (CsPI) and 4-aminobenzoic acid (ABA). Both the presence of PbS QDs and the specific capping used have a significant effect on the properties of the deposited perovskite layer, which affects, in turn, the photovoltaic performance. For all capping ligands used, the inclusion of PbS QDs leads to the formation of perovskite films with larger grain size, improving, in addition, the crystalline preferential orientation and the crystallinity. Yet, differences between capping agents were observed. The use of QDs with ABA capping had higher impact on the morphological properties while the employment of CsPI ligand was more effective on the optical properties of the perovskite films. Taking advantage of the improved properties, PSCs based on the perovskite films with embedded PbS QDs exhibit an enhanced photovoltaic performance, observing the highest increase with ABA capping. Moreover, bulk recombination via trap states is reduced when the ABA ligand is used as capping of the PbS QD additives in the perovskite film. We demonstrate how surface chemistry engineering of PbS QD additives in solution-processed perovskite films opens a new approach towards the design of high quality materials, paving the way to improved optoelectronic properties and more efficient photovoltaic devices.
关键词： nucleation centers,PbS quantum dots,perovskite solar cells,photovoltaic performance,capping ligands
更新于2025-09-11 14:15:04
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Systematic control of the rate of singlet fission within 6,13-diphenylpentacene aggregates with PbS quantum dot templates
摘要： Lead chalcogenide quantum dots (QDs) are promising acceptors for photovoltaic devices that harness the singlet fission (SF) mechanism. The rate of singlet fission of polyacenes in the presence of QDs is a critical parameter in determining the performance of such devices. The present study demonstrates that the rates of SF in a pentacene derivative, 6,13-dipenylpentacene (DPP), are modulated by forming coaggregates with PbS QDs in aqueous dispersions. PbS QDs generally accelerate SF within DPP aggregates, and the extent of acceleration depends on the size of the QD. The average rate of SF increases from 0.074 ps-1 for DPP-only aggregates to 0.37 ps-1 within DPP-D co-aggregates for QDs with radius 2.2 nm, whereas co-aggregation with the smallest (r = 1.6 nm) and largest (r = 2.7 nm) QDs we tried only slightly change the SF rate. The rate variation is associated with (i) the density of surface ligands, which is influenced by the faceting of the PbS surface, and (ii) the local dielectric constant for the DPP. To accelerate SF, the ligands should be dense enough to provide sufficient affinity for DPP aggregates and effectively perturb the perpendicular alignment of DPP monomers within aggregates to increase the intermolecular coupling that promotes SF, but should not be too dense so as to form a low dielectric environment that disfavors SF. The study suggests that it is critical to consider the influence of the microenvironment of QD surface on photophysical processes when fabricating QD/organic hybrid devices.
关键词： pentacene,photovoltaic devices,PbS,quantum dots,singlet fission
更新于2025-09-11 14:15:04
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Cation‐Exchange Synthesis of Highly Monodisperse PbS Quantum Dots from ZnS Nanorods for Efficient Infrared Solar Cells
摘要： Infrared solar cells that utilize low-bandgap colloidal quantum dots (QDs) are promising devices to enhance the utilization of solar energy by expanding the harvested photons of common photovoltaics into the infrared region. However, the present synthesis of PbS QDs cannot produce highly efficient infrared solar cells. Here, a general synthesis is developed for low-bandgap PbS QDs (0.65–1 eV) via cation exchange from ZnS nanorods (NRs). First, ZnS NRs are converted to superlattices with segregated PbS domains within each rod. Then, sulfur precursors are released via the dissolution of the ZnS NRs during the cation exchange, which promotes size focusing of PbS QDs. PbS QDs synthesized through this new method have the advantages of high monodispersity, ease-of-size control, in situ passivation of chloride, high stability, and a “clean” surface. Infrared solar cells based on these PbS QDs with different bandgaps are fabricated, using conventional ligand exchange and device structure. All of the devices produced in this manner show excellent performance, showcasing the high quality of the PbS QDs. The highest performance of infrared solar cells is achieved using ≈0.95 eV PbS QDs, exhibiting an efficiency of 10.0% under AM 1.5 solar illumination, a perovskite-filtered efficiency of 4.2%, and a silicon-filtered efficiency of 1.1%.
关键词： PbS,quantum dots,nanorods,cation exchange,solar cells
更新于2025-09-11 14:15:04