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Solution-processable organic–inorganic hybrid perovskites are being widely investigated for many applications, including solar cells, light-emitting diodes, photodetectors, and lasers. Herein, we report, for the first time, successful fabrication of xerographic photoreceptors using methylammonium lead iodide (CH3NH3PbI3) perovskite as a light-absorbing material. With the incorporation of polyethylene glycol (PEG) into the perovskite film, the ion migration inherent to the perovskite material can be effectively suppressed, and the resulting photoreceptor exhibits a high and panchromatic photosensitivity, large surface potential, low dark decay, and high environmental resistance and electrical cycling stability. Specifically, the energies required to photodischarge one half of the initial surface potential (E0.5) are 0.074 μJ cm−2 at 550 nm and 0.14 μJ cm−2 at 780 nm, respectively. The photosensitivites outmatch those of the conventionally used organic pigments having narrow spectral responses. Our findings inform a new generation of highly efficient and low-cost xerographic photoreceptors based on perovskite materials.

A coupled-spiral interferometer is a compact photonic component employing a continuous coupling between the arms of the spiral. Strong resonances occur when phase matching between the arms is achieved. In this work, we present an integrated silicon nitride organic-hybrid laser which is based on such a coupled-spiral interferometer resonator. Optical excitation is achieved with a 450 nm laser diode. The emission wavelength of the organic-hybrid laser is at 613 nm in transverse-magnetic-like polarization. As the coherent light is generated and directly emitted into a single-mode optical waveguide on the photonic chip elaborate coupling of laser light from an external source can be avoided.

Tin-based halide perovskite materials have been successfully employed in lead-free perovskite solar cells, but the overall power conversion efficiencies (PCEs) have been limited by the high carrier concentration from the facile oxidation of Sn2+ to Sn4+ . Now a chemical route is developed for fabrication of high-quality methylammonium tin iodide perovskite (MASnI3 ) films: hydrazinium tin iodide (HASnI3 ) perovskite film is first solution-deposited using presursors hydrazinium iodide (HAI) and tin iodide (SnI2 ), and then transformed into MASnI3 via a cation displacement approach. With the two-step process, a dense and uniform MASnI3 film is obtained with large grain sizes and high crystallization. Detrimental oxidation is suppressed by the hydrazine released from the film during the transformation. With the MASnI3 as light harvester, mesoporous perovskite solar cells were prepared, and a maximum power conversion efficiency (PCE) of 7.13 % is delivered with good reproducibility.

Defects from grain interiors and boundaries of perovskite films cause significant nonradiative recombination energy loss, and thus perovskite films with controlled crystallinity and large grains is critical for improvement of both photovoltaic performance and stability for perovskite-based solar cells. Here, a methylamine (MA0) gas-assisted crystallization method is developed for fabrication of methylammonium lead iodide (MAPbI3) perovskite films. In the process, the perovskite film is formed via controlled release of MA0 gas molecules from a liquid intermediate phase MAPbI3·xMA0. The resulting perovskite film comprises millimeter-sized grains with (110)-uniaxial crystallographic orientation, exhibiting much low trap density, long carrier lifetime, and excellent environmental stability. The corresponding perovskite solar cell exhibits a power conversion efficiency (PCE) of ~ 21.36%, which is among the highest reported for MAPbI3-based devices. This method provides important progress towards the fabrication of high-quality perovskite thin films for low-cost, highly efficient and stable perovskite solar cells., Suppressing grain boundaries and defects in perovskite solar cells remains a quest to address the efficiency and stability issues. Here, the authors use methylamine gas for assisting the growth of uniaxial-oriented perovskite thin films with millimeter-sized grains.

Solution-processed polycrystalline perovskite films have detrimental defects in the bulk and surfaces/grain boundaries, especially the uncoordinated lead ions (Pb2+) with low formation energy, limiting both the performance and stability of the photovoltaic devices. In this work, a conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT) is incorporated into a bulk perovskite film by a facile in-situ polymerization method, where 5-bromo-2,3-dihydro-thieno[3,4-b] [1] , [4] dioxine (BEDOT) as monomer is directly added to a perovskite precursor solution and then in-situ polymerized within the perovskite film during the film formation. The PEDOT is chemically anchored at the surface and grain boundaries of the perovskite film via interaction of sulfur and oxygen atoms in PEDOT with uncoordinated lead ions in the perovskite, passivating the surface and bulk defects and also improving the charge extraction efficiency in the solar cell. Moreover, robust and hydrophobic properties of PEDOT can enhance the thermal and moisture resistance of the perovskite film. As a result, a champion power conversion efficiency (PCE) of 22.58% is achieved, along with significantly enhanced environmental, thermal, and light-soaking stability.

One of the major barriers for a widespread commercial uptake of silicon nitride photonic integrated circuits for cost-sensitive applications is the lack of low-cost monolithically integrated laser light sources directly emitting into single-mode waveguides. In this work, we demonstrate an optically pumped organic solid-state slot-waveguide distributed feedback laser designed for a silicon nitride organic hybrid photonic platform. Pulsed optical excitation of the gain medium is achieved by a 450 nm laser diode. The optical feedback for lasing is based on a second-order laterally coupled Bragg grating with a slot-waveguide core. Optimized material gain properties of the organic dye together with the increased modal gain of the laser mode arising from the improved overlap of the slot-waveguide geometry with the gain material enable single-mode lasing at a wavelength of 600 nm. The straightforward integration and operation with a blue laser diode leads to a cost-effective coherent light source for photonic integrated devices.

We report several PECVD silicon nitride photonic building blocks required for the implementation of a CMOS-compatible photonic integrated circuit technology platform operating in the 850 nm and 600 nm wavelength domain. In particular, for the 850 nm wavelength region we discuss a low-loss broadband 1x2 power splitter and a loop mirror. In the 600 nm wavelength region, we present new results on an optically pumped integrated dye-doped polymer laser that couples its light directly into a silicon nitride waveguide. Moreover, we discuss design considerations for a waveguide based gas sensing concept detecting target gas specific absorption changes in a thin dye-doped polymer cladding layer.

Coherent light sources are a key component for photonic integrated circuits. Organic solid-state lasers can be monolithically integrated and are highly cost-effective. We report silicon nitride organic hybrid laser designs pumped with a laser diode.

Currently, the hybrid perovskite solar cells were exclusively dominated by the Pb or Sn-based perovskite materials, and these materials, however, exhibit long term instabilities associated with ambient hydrolysis and oxidation, limiting their widespread applications. In this work, two layered cupric bromide hybrid perovskite compounds are prepared as light absorbers for application in heterojunction solar cells. The perovskite layers can be deposited from the solutions of the as-prepared perovskites or directly from their precursor solutions at ambient condition. Their preliminary phoyovoltaic performance was carried out in mesoporous TiO2 heterojunction solar cells. (c) 2015 Elsevier B.V. All rights reserved.

Poly(3-hexylthiophene) (P3HT) was used in a solid-state dye-sensitized solar cell (S-DSC) with a broad-absorption metal-free organic dye sensitizer 1,2,4,5-benzenetetracarboxylic acid (BzTCA). Under full-sunlight irradiation (AM 1.5 G, 100 mW/cm 2 ), an overall conversion efficiency of 3.21% was achieved, which represents one of the highest efficiencies reported in an S-DSC. Our results indicate that the P3HT polymer is a promising material as both a hole conductor and an assistant sensitizer in the fabrication of solid-state DSCs.

Three diketopyrrolopyrrole (DPP) dyes ( ICD-3 , ICD-4 and ICD-5 ) with a D-π-A conjugation were designed and synthesized, where a symmetric phenyl-DPP-phenyl unit was used to connect a substituted diphenylamine and a thienyl acrylic acid, and two n -hexyl or 2-ethyl-hexyl chains were introduced on the periphery of the DPP macrocycle. The dyes were characterized by photophysical, electrochemical, and density functional theory calculations. Among the three dyes, the ICD-5 -based DSC afforded the best photovoltaic performance: a short circuit photocurrent density ( J sc ) of 16.34 mA/cm 2 , an open circuit voltage ( V oc ) of 753 mV, and a fill factor ( FF ) of 0.74, corresponding to an overall conversion efficiency ( η ) of 9.10% using I − / I 3 − redox couple-based liquid electrolyte under AM 1.5 conditions. The experimental results demonstrate that the DPP-based sensitizer is a promising option for DSCs, and rational molecular engineering is crucial for constructing highly efficient charge transfer sensitizers.

Pyrazino[2,3-g]quinoxaline was first employed as a π-linker in D–π–A type dyes, exhibiting an unusually broad and intense spectral absorption ranged from the visible to the near infrared region. A power conversion efficiency of 6.86% was achieved in dye-sensitized solar cells.

The provision of a coherent light source is a prerequisite for a variety of photonic integrated circuits. The integration of semiconductor laser diodes in disposable photonic devices in fields such as biosensing is, however, impeded by the competitive pricing in this application area. In this work, we demonstrate lasing of an alternative laser light source, namely an integrated hybrid organic solid-state distributed feedback laser for a silicon nitride photonic platform. The laser is optically pumped with a high power 450 nm laser diode and emits in the visible at 630 nm into a waveguide taper to reduce the cross-section to a single mode geometry. Inkjet printing of the organic gain medium enables a local, cost-effective, and flexible processing technology. The fabrication of the presented coherent light source is CMOS compatible and therefore highly interesting for co-integrated sensing platforms.

The optimization of material gain in optically pumped dye-doped polymer thin films is an important task in the development of organic solid-state lasers. In this work, we present a theoretical model that accommodates the influence of concentration quenching on material gain and employ it to study the novel dye molecule 2-(4-(bis(4-(tert-butyl)phenyl)amino)benzylidene)malononitrile (PMN) and the well-established dye molecule 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM) embedded in poly(methyl methacrylate) (PMMA). Polycarbonate was tested as an alternative host material for PMN. The material gain in these dye-doped polymer thin films was determined by the variable stripe length method. The inclusion of concentration quenching in the material gain expression is able to significantly reduce the overestimation of the gain efficiency inherent to a linear model., Comment: \copyright{} 2019 Optical Society of America. Users may use, reuse, and build upon the article, or use the article for text or data mining, so long as such uses are for non-commercial purposes and appropriate attribution is maintained. All other rights are reserved

Pyrene is an alternant polycyclic aromatic hydrocarbon consisting of four fused benzene rings with a large, flat aromatic system, showing high thermal stability, extensive electron delocalization and electron accepted nature. In this work, pyrene was firstly employed as π-conjugated bridge to construct electron donor–π–electron acceptor (D–π–A) organic dyes, where diarylamine or indoline was used as donor, and cyanoacrylic acid as electron acceptor. The peryne-based dyes were employed as sensitizers in dye-sensitized solar cells, and give a short circuit photocurrent density (Jsc) of 12.1 mA/cm2, an open circuit voltage (Voc) of 0.71 V, and a fill factor (FF) of 0.71, corresponding to an overall conversion efficiency (η) of 6.1% under AM 1.5 conditions.

Dye-sensitized photoelectrochemical solar cells (DSCs) are one of the most promising alternatives to conventional inorganic devices owing to their potential low production costs and high conversion efficiencies. In a typical DSC, a mesoporous n-type TiO2 electrode, anchored with an electron-injecting sensitizer, acts as an photoanode for light absorption, and a platinized fluorine-doped tin oxide (FTO) glass as a passive cathode for catalysis of the electrolyte with a redox couple I /I3 , sandwiched between the two electrodes (n-DSC). In this n-DSC, light-induced electron injection from the excited sensitizer into the conduction band of TiO2 is followed by hole injection into the electrolyte, generating a photovoltage defined by the difference in chemical potential between the TiO2 photoanode and the electrolyte. On the other hand, a p-type semiconductor electrode (such as NiO) can be sensitized by a hole-injection sensitizer and used as a photocathode in combination with a Pt passive anode in a DSC (p-DSC). In this case, an opposite process occurs, with electron injection into the electrolyte and hole injection into the valence band of NiO, resulting in a photovoltage equal to the difference in chemical potential between the NiO photocathode and the electrolyte. With the combination of a photoanode and a photocathode in a single device (np-DSC), a tandem DSC has been advanced with a theoretical efficiency limitation well beyond that of a single junctionDSC (nor p-DSC). In this double junction tandem device, both the active electrodes are connected in series, and thus a high photovoltage, namely a sum of the photovoltages obtained in the corresponding p and n devices, can be expected, with the potential to dramatically improve the efficiency. Since the first report in 2000, the p-type NiO semiconductor has been extensively investigated, and efforts were mainly focused on the development of hole injection sensitizers for the electrode. In most reports, the NiO based pDSCs gave the very limited photocurrent densities of 1– 2 mAcm 2 and low open-circuit voltages Voc of typically < 150 mV, resulting in efficiencies of < 0.2%. Recently, a record conversion efficiency of 0.41% was achieved in a pDSC through a combinational optimization of NiO electrode, electrolyte, and sensitizer. The efficiency is encouraging, but is still low owing to the intrinsic limitation of the NiO electrode, where 30–40% of photons are absorbed by the NiO electrode itself, but made almost no photocurrent contribution to the device. Furthermore, the Voc is also limited by its high positive valence band energy level. Thus, it is necessary to develop new photocathodes to further improve the efficiency of the tandem device. Most recently, an acidtreated CdS quantum-dot-based electrode was reported as a photocathode, giving a photocurrent density (Jsc) of 0.1 mAcm 2 and open-circuit voltage of 111 mV. Herein, we present a selenium-based photocathode that was developed by deposition of selenium on the TiO2 electrode by an electrochemical deposition method. With this photocathode, a photoelectrochemical solar cell was prepared using a Pt counter electrode and a standard I /I3 electrolyte, exhibiting a cathodic photocurrent of 3.73 mAcm , an open-circuit voltage (Voc) of 318 mV, and an overall efficiency of 0.34% under AM1.5 (100 mWcm ) illumination. A tandem device was further constructed by replacing the Pt counter electrode with a conventional N719sensitized TiO2 anode, giving a Jsc of 2.72 mAcm , a Voc of 940 mV, and an overall efficiency of 0.98%. The tandem device is represented with an energy scale in Figure 1. For the preparation of the selenium-based photocathode, a 2.4 mm-thick porous TiO2 layer was firstly coated on a FTO glass substrate by the doctor blade technique with TiO2 paste (particle size 60 nm) synthesized according to a previous report. Then a thin selenium layer on the mesoporous TiO2 electrode was obtained by the electrochemical deposition method, which was widely used owing to its simplicity, good reproducibility, and controllable deposition fashion. Elemental selenium was deposited inside the mesoporous TiO2 film by reduction of selenite ions

The xerographic property has been studied in the double-layered photoreceptor device where azo/TiOPc composite is used as the charge-generation material (CGM) and p -diethylaminobenzaldehyde-α-naphthalenylphenylhydrazone (DENPH) or p -dimethylaminobenzaldehyde diphenylhydrazone (DMDPH) is used as the charge-transportation material (CTM) under the exposure of various spectral regions. The results show that the azo/TiOPc composites exhibit high photosensitivity not only in the visible and near-infrared regions, but also in the entire spectral ranges, indicating the co-enhancement effect. The UV–VIS spectra suggest that the absorption spectra of the azo/TiOPc composites are broadened. The composite mechanism is investigated through X-ray diffraction and ESR.

Regioregular poly(3-hexylthiophene) (P3HT) was employed as a hole transport material and assistant light absorber for the fabrication of a CdS quantum dot-sensitized solid-state solar cell, by which a power-conversion efficiency of 1.42% was achieved under an AM1.5 G (100 mW cm(-2)) condition.

In this communication, a novel bulk heterojunction solar cell based on an electron donor-acceptor conjugated triphenylamine dye was fabricated, and a high conversion efficiency of 1.23% was achieved under AM 1.5 illumination (100 mW cm(-2)).

Substituting pyrenes at the 2,7-positions is synthetically challenging because of the presence of a nodal plane in the HOMO and LUMO, which lies perpendicular to the molecule and passes through the 2- and 7-positions. Thus, there are few reports about 2,7-substituted pyrenes. Here, a distinct D–π–A structured 2,7-substituted pyrene dye ICP-3 was successfully synthesized, where a diphenylamine unit and thienyl acrylic acid moiety are located at C-2,7 positions of the pyrene, and the pyrene functions as a linker to bridge them. The DFT calculations show that no nodal plane through the 2- and 7-carbon atoms was observed in the HOMO and LUMO when the donor and the acceptor were attached, indicating effective charge transfer in the molecule upon light excitation. The ICP-3 was used as sensitizer for dye-sensitized solar cells, showing a power conversion efficiency of 4.1% under AM 1.5 conditions.

A novel tetrahydropyrene-based D–π–A organic dye D2 was designed and synthesized for the first time, featuring 4,5,9,10-tetrahydropyrene as a π conjugation linker to bridge the diphenylamine unit and the thienyl acrylic acid moiety. Its counterpart D1 was prepared for comparison, where biphenyl was used as the linker. Both dyes were characterized by photophysical, electrochemical, and theoretical computational methods. It was found that the introduction of two ethylene groups on the C2, C2′ and C6, C6′ of the biphenyl in D2 can prevent the rotation of the adjacent phenyl rings, and ensure the coplanarity of the bridge. As a result, the maximum absorption peak (λmax) of D2 was 29 nm red shifted as compared with D1. Nanocrystalline TiO2-based dye-sensitized solar cells were fabricated using the dyes as light harvesting sensitizers, and exhibited power conversion efficiencies of 6.75% for D2 and 4.73% for D1 under AM 1.5 conditions.

A novel ruthenium-free organic dye, 3-(5-(4-(di-p-tolylamino)styryl)-2,3-dihydrothieno[3,4-b][1,4]dioxin-7-yl)-2-cyanoacrylic acid (coded as H01), is synthesized in a short sequence. The dye is composed of a di(p-tolyl)phenylamino moiety as an electron donor, a cyanoacrylate moiety as an electron acceptor, and an ethylenedioxythiophene unit as the spacer to bridge the donor and the acceptor. The as-prepared H01 dye is employed as a sensitizer in a dye-sensitized nanocrystalline TiO2 solar cell, and the short-circuit photocurrent density (Jsc), open-circuit voltage (Voc), and fill factor (ff) of the device under AM 1.5 (100 mW cm−2) irradiation, are 15.22 mA cm−2, 0.67 V, and 0.72, respectively, corresponding to an overall conversion efficiency (Eff) of 7.33%.

In this paper, we report our recent advances in the development of CMOS compatible PECVD silicon nitride waveguide based photonic key building blocks for optical coherence tomography (OCT) in the 850 nm wavelength region and for biosensing applications in the visible domain around 650 nm wavelength. We discuss the design and experimental verification of compact low-loss waveguide bends, broadband couplers with varying power splitting ratios required for PIC based OCT systems, arrayed waveguide gratings for spectral domain OCT, and a monolithically integrated optically pumped organic solid-state laser for low-cost biosensing applications.