Bulk optical components are conventionally used to control light. However, bulk optical components are limited by optical loss and ability for miniaturization. To address this problem, we developed soft multimaterial photonic devices. The theoretical predictions and experimental results are compared with the device characterization. Plasmonic super-resolution imaging based on this device is presented as an example. We find the result of plasmonic super-resolution imaging enabled by the compact design is comparable to commercial devices.
Near-infrared (NIR) organic photodetectors with high detectivity are fabricated with an organic electron blocking layer (EBL) with an appropriate energy band alignment. To avoid damage to a preceding organic electron blocking layer during a subsequent coating of an organic photoactive layer, cross-linking technology using a novel photoinitiator is used for an EBL. Poly-TPD is used as an EBL due to its appropriate energy band alignment with an NIR organic sensitizing layer. A ternary blend film composed of PTB7-Th, COi8DFIC, and PC71BM are used as a NIR sensitizing layer with strong photosensitivity in multi-spectral (UV-Visible-NIR) wavelengths of 300-1,000 nm.
Metal-halide perovskites are emerging as an intriguing class of semiconductors with significant potential for photovoltaics. Here, several perovskites are discussed that have been assessed via various experimental techniques to determine the effects of their composition, dimensionality, and structural stability on hot carriers and polaron formation. It will be shown that polarons formed in these systems are strongly affected by the binding energy and nature of the excitons in the materials. Notably, the hot carrier dynamics in perovskites is strongly affected by their low thermal conductivity, which inhibits the dissipation of heat in the material.
Metal halide perovskites are a leading contender to disrupt not only terrestrial photovoltaic (PV) markets, but also the proliferating space PV markets. This is due to their impressive power conversion efficiencies, potentially low cost, and adaptability to flexible architectures. Here we assess the stability of three perovskite systems; a mixed Pb-Sn perovskite, and two mixed cation-triple halide systems. In all cases high tolerance to proton irradiation was observed. However, in the case of the mixed Pb-Sn system, irreversible decomposition of the perovskite along with the increased prevalence of defects was observed with thermal cycling. In the case of the mixed cation triple halides remarkable stability was demonstrated, in addition to self-healing, the results of which will be described here.
Halide perovskites are very attractive for solution-processed visible and near-IR sensing applications due to their intrinsic advantages such as excellent photosensitivity, bandgap tunability, broadband sensitivity, high charge transport capability, and solution-processability. Unlike Pb-based perovskites, which cannot be tuned to below 1.48 eV, Pb-Sn mixed halide perovskites exhibit low bandgaps of 1.2-1.3 eV. Due to the low bandgap, these Pb-Sn mixed halide perovskite can absorb light till 1000nm making them a viable alternative to Silicon as the visible and near-IR broadband photodetectors. However, the low-bandgap nature of Pb-Sn mixed perovskites also causes large levels of electron and hole injection from anode and cathode, thus leading to high dark current. To mitigate the issue of charge injection, therefore, it is important to have an electron blocking layer (EBL) and a hole blocking layer (HBL) inserted between the electrodes and the Pb-Sn mixed perovskite photodetectors.
Polymer solar cells (PSCs) have attracted increasing attention due to their inexpensive, flexible, light weight
and large area device fabrication. However, the efficiency of PSCs is still not yet sufficient for large scale
implementation. Many approaches have been proposed to enhance the efficiency of PSCs. In addition to using new
materials and new device structure, the performance of polymer solar cells can also be improved using efficient interface
layer between the electrode and active layer. Here, we studied the effect of MoO3 as an anode interlayer on both small
molecule and polymer photovoltaic cells. Significant improvement has been observed in the performance of PSCs and
the power conversion efficiency (PCE) of the cell with a MoO3 interlayer can be enhanced by ~15% comparing to the
cells with a PEDOT:PSS interlayer. This improved device performance is attributed to the combined effect of efficient
charge extraction and the reduction in series resistance of device.
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