Wai-Lun Chan

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The surface of high fluence ion-sputtered Si(111) was found to exhibit a rich variety of transient one- and two-dimensional topographies that may be exploited as tunable self-organized arrays of nanostructures. Such transient effects are only partially described by analytical models of sputter patterning. However, a discrete atom kinetic Monte Carlo(More)
Photocurrent generation in organic photovoltaics (OPVs) relies on the dissociation of excitons into free electrons and holes at donor/acceptor heterointerfaces. The low dielectric constant of organic semiconductors leads to strong Coulomb interactions between electron-hole pairs that should in principle oppose the generation of free charges. The exact(More)
Multiple exciton generation (MEG) refers to the creation of two or more electron-hole pairs from the absorption of one photon. Although MEG holds great promise, it has proven challenging to implement, and questions remain about the underlying photo-physical dynamics in nanocrystalline as well as molecular media. Using the model system of pentacene/fullerene(More)
One strategy to improve solar-cell efficiency is to generate two excited electrons from just one photon through singlet fission, which is the conversion of a singlet (S(1)) into two triplet (T(1)) excitons. For efficient singlet fission it is believed that the cumulative energy of the triplet states should be no more than that of S(1). However, molecular(More)
The absorption of one photon by a semiconductor material usually creates one electron-hole pair. However, this general rule breaks down in a few organic semiconductors, such as pentacene and tetracene, where one photon absorption may result in two electron-hole pairs. This process, where a singlet exciton transforms to two triplet excitons, can have quantum(More)
The efficiency of a conventional solar cell may be enhanced if one incorporates a molecular material capable of singlet fission, that is, the production of two triplet excitons from the absorption of a single photon. To implement this, we need to successfully harvest the two triplets from the singlet fission material. Here we show in the tetracene(More)
Polo-like kinase 1 (Plk1) is well-known for taking part in cell cycle progression and regulation. Using small molecules for Plk inhibition has been well documented in the literature. However, there are several intrinsic and intractable problems associated with this approach. For example monitoring small molecule Plk inhibitors as anti-tumor agents in(More)
Singlet fission, the creation of two triplet excitons from one singlet exciton, is being explored to increase the efficiency of solar cells and photo detectors based on organic semiconductors, such as pentacene and tetracene. A key question is how to extract multiple electron-hole pairs from multiple excitons. Recent experiments in our laboratory on the(More)
Exciton or energy transport in organic crystals is commonly described by a series of incoherent hoppings. This picture is no longer valid if the transport range is on the order of the exciton coherent (or delocalization) size. However, coherent effects are often neglected because the exciton wave function generally localizes to a few molecules within an(More)
An amphiphilic water-soluble ytterbium complex which is photo-selective, functional and Golgi apparatus specific has been designed as a responsive dual probe capable of sensitizing emission within the biological window (660 and 750 nm), generating the singlet oxygen (Φ(Δ) = 0.45) and triggering local cell damage only upon exposure to visible and(More)