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Rational design of pyrrolopyrrole-aza-BODIPY-based acceptora??donora??acceptor triads for organic photovoltaics application
摘要： Acceptor-donor-acceptor triads consisting of diketopyrrolopyrrole (DPP) or pyrrolopyrrole aza-BODIPY (PPAB) or both as acceptors and cyclopentadithiophene as a donor were rationally designed for near infrared (NIR) photovoltaics application. Among them, the PPAB-based triad exhibited the highest power conversion efficiency of 3.88% owing to the panchromatic absorption in the UV/vis/NIR regions.
关键词： pyrrolopyrrole-aza-BODIPY,organic photovoltaics,acceptor-donor-acceptor triads,near infrared photovoltaics
更新于2025-09-23 15:19:57
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Mixed Lead Halide Passivation of Quantum Dots
摘要： Infrared-absorbing colloidal quantum dots (IR CQDs) are materials of interest in tandem solar cells to augment perovskite and cSi photovoltaics (PV). Today’s best IR CQD solar cells rely on the use of passivation strategies based on lead iodide; however, these fail to passivate the entire surface of IR CQDs. Lead chloride passivated CQDs show improved passivation, but worse charge transport. Lead bromide passivated CQDs have higher charge mobilities, but worse passivation. Here a mixed lead-halide (MPbX) ligand exchange is introduced that enables thorough surface passivation without compromising transport. MPbX–PbS CQDs exhibit properties that exceed the best features of single lead-halide PbS CQDs: they show improved passivation (43 ± 5 meV vs 44 ± 4 meV in Stokes shift) together with higher charge transport (4 × 10-2 ± 3 × 10-3 cm2 V-1 s-1 vs 3 × 10-2 ± 3 × 10-3 cm2 V-1 s-1 in mobility). This translates into PV devices having a record IR open-circuit voltage (IR Voc) of 0.46 ± 0.01 V while simultaneously having an external quantum efficiency of 81 ± 1%. They provide a 1.7× improvement in the power conversion efficiency of IR photons (>1.1 μm) relative to the single lead-halide controls reported herein.
关键词： ligand exchange,infrared photovoltaics,quantum dots,nanomaterials
更新于2025-09-11 14:15:04
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Manipulation of Phase-Transfer Ligand-Exchange Dynamics of PbS Quantum Dots for Efficient Infrared Photovoltaics
摘要： Chemical surface treatment of colloidal quantum dots (CQDs) by phase-transfer ligand exchange (PTLE) is essential to implement highly densified, well-passivated CQD films for optoelectronic applications, such as infrared photovoltaics, light-emitting diodes and photodetectors. The PTLE, however, involves parallel and interactional processes of ligand exchange, phase transfer, and surface passivation of CQDs, which renders the optimization of PTLE still challenging. Herein, we explored the action mechanism of a widely-used additive, ammonium acetate (AA), on the PTLE of PbS CQDs in order to recognize the dynamic balance during the PTLE process and its impact on the performance of colloidal quantum dot solar cells (CQDSCs). Our research definitely shows that AA additive can modify the dynamics of PTLE by participating in all the three processes, and the amount of AA significantly influences the defect passivation and colloidal stability of PbS CQDs. At an appropriate concentration (~50 mM) of AA, PbS CQDs are well iodide-passivated by the PTLE, and the fabricated CQDSCs achieve the PCE of ~10% associated with the improved carrier transport and the reduced trap-assisted carrier recombination. However, excessive AA causes the trace residual AA on the CQD surface, resulting in the insufficient surface passivation of PbS CQDs and trap issues of CQDSCs. The double-edged sword effect of AA additive on the PTLE, demonstrated in our work, suggests that realizing the dynamic balance of different processes during PTLE is crucial for the further performance promotion of CQDSCs.
关键词： infrared photovoltaics,ammonium acetate,phase-transfer ligand exchange,colloidal quantum dots,surface passivation
更新于2025-09-11 14:15:04