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Colloidal quantum dot solar cells (CQDSCs) are attracting growing attention owing to significant improvements in efficiency. However, even the best depleted-heterojunction CQDSCs currently display open-circuit voltages (V_OCs) at least 0.5 V below the voltage corresponding to the bandgap. We find that the tail of states in the conduction band of the metal oxide layer can limit the achievable device efficiency. By continuously tuning the zinc oxide conduction band position via magnesium doping, we probe this critical loss pathway in ZnO–PbSe CQDSCs and optimize the energetic position of the tail of states, thereby increasing both the V_OC (from 408 mV to 608 mV) and the device efficiency.

A fundamental loss mechanism in depleted-heterojunction colloidal quantum dot solar cells (CQDSCs) is identified to arise from the metal oxide conduction band tail. This loss is studied in ZnO–PbSe CQDSCs and minimized by optimizing the ZnO–PbSe conduction band alignment via magnesium-doping of the ZnO. Significant improvements in open-circuit voltage and efficiency are achieved.

The optical energy gap of as-grown MoS₂ flakes from chemical vapor deposition can be modulated from 1.86 eV (667 nm) to 1.57 eV (790 nm) by a vapor phase selenization process. This approach, replacing one chalcogen by another in the gas phase, is promising in modulating the optical and electronic properties of other transition metal dichalcogenide monolayers.

A simple and cost-effective microfluidic design at the scale of the channels in which sperm swim towards an egg is reported. In these channels, human and mouse sperm movement is quantitatively investigated. As described on page 3374 by E. Tüzel, U. Demirci, and co-workers, a significant role is discovered for mouse sperm exhaustion using experiments and coarse-grained computational modeling. The experimental results are recapitulated by the computational model when mouse sperm is modeled with an average exhaustion time. On the other hand, exhaustion does not play a significant role in human sperm sorting for up to 1 h incubation. The presented platform is broadly applicable to multiple areas including reproductive medicine, veterinary sciences, cryobiology, biobanking, wild life preservation, and cell-taxis studies.

Among the interests in the application of quantum dots (QDs), the bandgap tuning is of key importance in controlling their material properties. The bandgap of a QD can be adjusted by adopting a variety of different physicochemical methods. Herein, a novel way of the bandgap tuning is developed in an Ag2S-based QD system by suitably quenching the transformation from monoclinic Ag2S to cubic Ag and by subsequently inducing a lattice-distorted region of ≈1-nm-scale in a QD. The two distinct crystalline phases of Ag2S and Ag coexisting with the lattice-distorted region are experimentally demonstrated by visually showing this remarkable coexistence in a QD. A new approach is presented to the bandgap tuning (2.51 to 1.64 eV) and enhancing optical properties by suitably tailoring the degree of the lattice-distorted region in a QD. This conceptual method could pave a new way to utilizing quantum effects in various QD applications.

Two distinct crystalline phases of Ag₂S and Ag that coexist with a lattice-distorted region are experimentally demonstrated in a quantum dot (QD). A new approach to bandgap tuning (2.51 to 1.64 eV) and enhancing optical properties is presented by suitably tailoring the degree of the lattice-distorted region within the QD.