Systematic control of the rate of singlet fission within 6,13-diphenylpentacene aggregates with PbS quantum dot templates
Systematic control of the rate of singlet fission within 6,13-diphenylpentacene aggregates with PbS quantum dot templates
复制标题
使用 PbS 量子点模板系统控制 6,13-二苯基并五苯聚集体中的单线态裂变速率
DOI：
10.1039/c8fd00157j
复制
发表时间：
2019
影响因子：
3.4
通讯作者：
Weiss, Emily A.
中科院分区：
文献类型：
--
作者：
Wang, Chen;Kodaimati, Mohamad S.;Lian, Shichen;Weiss, Emily A.
铅硫族化合物量子点（QD）是利用单重态裂变（SF）机制的光伏器件的有前途的受体。在量子点存在下，多并苯的单线态裂变速率是决定这种器件性能的关键参数。本研究表明，SF在并五苯衍生物，6，13-二苯基蒽（DPP）的速率，调制通过形成与PbS量子点在水性分散体的共聚集体。PbS QD通常加速DPP聚集体内的SF，并且加速的程度取决于QD的大小。SF的平均速率从仅DPP聚集体的0.074 ps-1增加到半径为2.2 nm的QD的DPP-D共聚集体中的0.37 ps-1，而我们尝试的最小（r = 1.6 nm）和最大（r = 2.7 nm）QD的共聚集体仅轻微改变SF速率。速率变化与（i）表面配体的密度有关，这受PbS表面的刻面影响，以及（ii）DPP的局部介电常数。为了加速SF，配体应该足够密集以提供对DPP聚集体的足够亲和力，并有效地扰乱聚集体内DPP单体的垂直排列以增加促进SF的分子间偶联，但不应该太密集以形成不利于SF的低介电环境。该研究表明，它是至关重要的，以考虑量子点表面的微环境对量子点/有机杂化器件的光物理过程的影响。
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-diphenylanthracene (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 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 the QD surface on photophysical processes when fabricating QD/organic hybrid devices.