Pressurized Back-Junction Doping via Spray-Coating Silver Nanowires Top Electrodes for Efficient Charge Collection in Bifacial Colloidal PbS Quantum Dot Solar Cells.

Colloidal PbS quantum-dot solar cells (QDSCs) have long suffered from inefficient charge collection near the back-junction due to the lack of p-doping strategy, rendering their bifacial photovoltaic applications unsuccessful. Here, we report highly efficient photocarrier collection in bifacial colloidal PbS QDSCs by exploiting spray-coated silver nanowires (AgNWs) top electrodes. During our spray-coating process, pressurized Ag diffusion occurred toward the active layer, which induced effective p-doping and deep-level passivation.

Dynamic one-shot target detection and classification using a pseudo-Siamese network and its application to Raman spectroscopy.

Target detection and classification by Raman spectroscopy are important techniques for biological and chemical defense in military operations. Conventionally, these techniques preprocess the observed spectra using smoothing or baseline correction and apply detection algorithms like the generalized likelihood ratio test, independent component analysis, nonnegative matrix factorization, . These conventional detection algorithms need preprocessing and multiple shots of Raman spectra to get a reasonable accuracy.

Direct Acoustic Imaging Using a Piezoelectric Organic Light-Emitting Diode.

Conventional ultrasonic imaging requires acoustic scanning over a target object using a piezoelectric transducer array, followed by signal processing to reconstruct the image. Here, we report a novel ultrasonic imaging device that can optically display an acoustic signal on the surface of a piezoelectric transducer. By fabricating an organic light-emitting diode (OLED) on top of a piezoelectric crystal, lead zirconate titanate (PZT), an acousto-optical piezoelectric OLED (p-OLED) transducer is realized, converting an acoustic wave profile directly to an optical image.

Thin Ag Precursor Layer-Assisted Co-Evaporation Process for Low-Temperature Growth of Cu(In,Ga)Se Thin Film.

Achieving favorable band profile in low-temperature-grown Cu(In,Ga)Se thin films has been challenging due to the lack of thermal diffusion. Here, by employing a thin Ag precursor layer, we demonstrate a simple co-evaporation process that can effectively control the Ga depth profile in CIGS films at low temperature. By tuning the Ag precursor thickness (∼20 nm), typical V-shaped Ga gradient in the copper indium gallium diselenide (CIGS) film could be substantially mitigated along with increased grain sizes, which improved the overall solar cell performance.

Formation of Perovskite Heterostructures by Ion Exchange.

Thin-film optoelectronic devices based on polycrystalline organolead-halide perovskites have recently become a topic of intense research. Single crystals of these materials have been grown from solution with electrical properties superior to those of polycrystalline films. In order to enable the development of more complex device architectures based on organolead-halide perovskite single crystals, we developed a process to form epitaxial layers of methylammonium lead iodide (MAPbI) on methylammonium lead bromide (MAPbBr) single crystals.

Vertical Organic Field-Effect Transistors for Integrated Optoelectronic Applications.

Direct integration of a vertical organic field-effect transistor (VOFET) and an optoelectronic device offers a single stacked, low power optoelectronic VOFET with high aperture ratios. However, a functional optoelectronic VOFET could not be realized because of the difficulty in fabricating transparent source and gate electrodes. Here, we report a VOFET with an on/off ratio up to 10(5) as well as output current saturation by fabricating a transparent gate capacitor consisting of a perforated indium tin oxide (ITO) source electrode, HfO2 gate dielectric, and ITO gate electrode.

Inorganic UV-Visible-SWIR Broadband Photodetector Based on Monodisperse PbS Nanocrystals.

Solution-processed inorganic UV-visible short-wave-infrared photodetectors with light sensitivity from 350 nm to 2000 nm are fabricated using highly monodispersed large PbS NCs. These devices showed detectivity values over 1 × 10(11) Jones from 350 nm to 2000 nm, and a maximum detectivity value of 1.2 × 10(12) Jones at 1800 nm.

All solution-processed inorganic/organic hybrid permeable metal-base transistor.

All solution-processed inorganic/organic hybrid permeable-base transistor (PMBT) based on nickel oxide emitter and P3HT collector is developed. Due to the high charge injection properties of nickel oxide and spontaneously formed nano-pinholes in the base electrode, the devices exhibit high common-base and common-emitter current gains up to 0.98 and 304, respectively with saturated output current.