Fundamentals, Advances, and Artifacts in Circularly Polarized Luminescence (CPL) Spectroscopy.

Objects are chiral when they cannot be superimposed with their mirror image. Materials can emit chiral light with an excess of right- or left-handed circular polarization. This circularly polarized luminescence (CPL) is key to promising future applications, such as highly efficient displays, holography, sensing, enantiospecific discrimination, synthesis of drugs, quantum computing, and cryptography.

A Sensitizer of Purpose: Generating Triplet Excitons with Semiconductor Nanocrystals.

The process of photon upconversion promises importance for many optoelectronic applications, as it can result in higher efficiencies and more effective photon management. Upconversion via triplet-triplet annihilation (TTA) occurs at low incident powers and at high efficiencies, requirements for integration into existing optoelectronic devices. Semiconductor nanocrystals are a diverse class of triplet sensitizers with advantages over traditional molecular sensitizers such as energetic tunability and minimal energy loss during the triplet sensitization process.

Mechanistic insight into CdSe nanoplatelet-sensitized upconversion: size and stacking induced effects.

CdSe nanoplatelets (NPLs) have been reported as triplet sensitizers for photon upconversion (UC). However, their UC quantum yields lag behind more conventional systems. Here, we take advantage of their one-dimensional quantum confinement to decouple effects caused by the energetic driving force and lateral size.

Scratching the Surface: Passivating Perovskite Nanocrystals for Future Device Integration.

Metal halide perovskite materials have recently upended the field of photovoltaics and are aiming to make waves across a multitude of other fields and applications. Recently, perovskite nanocrystals have been synthesized and are rapidly outpacing traditional semiconductor nanocrystals in application driven fields due to their inherent defect tolerance and facile tunability, resulting in high photoluminescent quantum yields and efficient devices. Future improvements to perovskite nanocrystals toward device driven applications must come at the perovskite surface.

Mixed halide bulk perovskite triplet sensitizers: Interplay between band alignment, mid-gap traps, and phonons.

Photon upconversion, particularly via triplet-triplet annihilation (TTA), could prove beneficial in expanding the efficiencies and overall impacts of optoelectronic devices across a multitude of technologies. The recent development of bulk metal halide perovskites as triplet sensitizers is one potential step toward the industrialization of upconversion-enabled devices. Here, we investigate the impact of varying additions of bromide into a lead iodide perovskite thin film on the TTA upconversion process in the annihilator molecule rubrene.

Perovskite-sensitized upconversion bingo: Stoichiometry, composition, solvent, or temperature?

Triplet-triplet annihilation-based photon upconversion (UC) using bulk perovskite sensitizers has been previously shown to facilitate efficient UC at low fluences. However, the fabrication of the UC devices has not been fully optimized; thus, there is room for improvement. Here, we apply techniques that have been successful in enhancing the performance of perovskite solar cells in order to also improve perovskite-sensitized UC devices.

Kitchen Spectroscopy: Shining a (UV) Light on Everyday Objects.

Fluorescent objects often lead to a sense of joy and intrigue. While the current COVID-19 pandemic limits the synthesis of "glowy things" like quantum dots, many household objects fluoresce, providing an opportunity to brighten your day while learning fundamental chemistry.

Influence of Triplet Diffusion on Lead Halide Perovskite-Sensitized Solid-State Upconversion.

The emerging field of lead halide perovskite-sensitized triplet-triplet annihilation (TTA) in rubrene shows great promise in upconversion applications. By rapidly transferring single charge carriers instead of bound triplet states, perovskites enable a high triplet population in rubrene, yielding low I values. In this contribution, we investigate the role of the triplet population on the upconverted emission.