CsPbI3 Perovskite Quantum Dots Research Articles

Passivation of 2D Cs2PbI2Cl2 Nanosheets for Efficient and Stable CsPbI3 Quantum Dot Solar Cells.

Inorganic CsPbI3 perovskite quantum dots (PQDs) possess remarkable optical properties, making them highly promising for photovoltaic applications. However, the inadequate stability resulting from internal structural instability and the complex external surface chemical environment of CsPbI3 PQDs has hindered the development of CsPbI3 PQD solar cells (PQDSCs). In this work, the capping layer composed of inorganic two-dimensional (2D) Ruddlesden-Popper (RP) phase Cs2PbI2Cl2 nanosheets (NSs) is introduced, which may be effectively treated to improve the surface properties of the CsPbI3 PQD film. This modification serves to passivate defects by filling cesium and iodine vacancies while optimizing the energy band arrangement and preventing humidity intrusion, leading to the meliorative stability and photovoltaic performance. The optimized CsPbI3 PQDSCs achieve an enhanced power conversion efficiency (PCE) of 14.73%, with the superb stability of only a 16% efficiency loss after being exposed to ambient conditions (30 ± 5% RH) for 432 h.

Modified surface ligand management of CsPbI3 perovskite quantum dots enables efficient and stable electroluminescent solar cells

Solution-processed CsPbI3 perovskite quantum dots (PQDs) have attracted enormous attention in both photovoltaic and electroluminescent applications in recent years. However, the surface defects of CsPbI3 PQDs in the ligand exchange procedure still suffer the challenge of imperfect passivation, leading to poor device performance and ambient stability. In this work, we propose a modified surface ligand management to deposit CsPbI3 PQD films using a layer-by-layer (LBL) solid-state exchange strategy, and its applications in photovoltaic and electroluminescent devices are studied. The conjugated phenethylammonium iodide (PEAI) ligand, acting as a short-chain ligand with a phenyl group (PEA+ ion) for encapsulating the CsPbI3 PQDs during the LBL procedure, which can both realize enhanced inter-dot coupling and defects passivation compared with conventional post-treatments. We further demonstrate the balanced transport and injection of electrons and holes within the PEAI-LBL based CsPbI3 PQD films. With this approach, the CsPbI3 PQD solar cells based on PEAI-LBL yielded a champion power conversion efficiency (PCE) of up to 14.18% with a high open voltage of 1.23 V, along with obviously electroluminescent red emission properties in one device. Meanwhile, the unencapsulated devices exhibited excellent stability under a high-humidity environment. This strategy should accelerate advancement in utilizing PQDs for bifunctional optoelectronic applications.

Photoluminescent Bi-doped CsPbX3 (X: Br, I) perovskite quantum dots for optoelectronic devices

Abstract Perovskite quantum dots (PQDs) became a hot spot in recent years due to their amazing properties, such as the high photoluminescence quantum yield, tunable emission, and narrow bandwidth being important for their application in different optoelectronic devices. In this work, Bi-doped CsPbBr3 and Bi-doped CsPbI3 PQDs were synthesized through the hot-injection method and compared with pristine CsPbBr3 and CsPbI3 to analyze the effect of Bi and the halogen on their properties. In addition, all the samples were synthesized at 130°C, 150°C, and 170°C with the aim of analyzing the effect of the temperature. The results showed a wide range of the emission wavelength from around 500 nm (Bi-doped CsPbBr3) to 630 nm (Bi-doped CsPbI3) as a consequence of the effect of the halogen in “X” position and a slight blueshift in the main photoluminescence emission band after doping the pristine quantum dots with Bi. Graphical abstract Impact statement We believe that the work in this article represents an important advance in the application of perovskite quantum dots in optoelectronics applications, such as in LEDs or lasers. We report here the synthesis and characterization of Bi-doped CsPbX3 perovskite quantum dots (PQDs), being X: Br and I. These Bi-doped PQDs show a wide range of the emission wavelength from around 500 nm (Bi-doped CsPbBr3) to 630 nm (Bi-doped CsPbI3) as a consequence of the effect of the halogen in “X” position and a slight blueshift in the main photoluminescence emission band after doping the pristine quantum dots with Bi. Therefore, they are good candidates to fabricate optoelectronic devices such as LEDs and lasers thanks to their high photoluminescence emission and their tunable emission.

Proton-Prompted Ligand Exchange to Achieve High-Efficiency CsPbI3 Quantum Dot Light-Emitting Diodes

HighlightsA new proton-promoted in situ ligand exchange strategy based on CsPbI3 quantum dots.The ligand exchange strategy maintains the quantum confinement effect of quantum dots and significantly improves the stability and photophysical properties of CsPbI3 quantum dots.The performance of light-emitting diodes based on CsPbI3 quantum dots is significantly improved, the external quantum efficiency is increased from 18.63% to 24.45%, and the half-operational lifetime is increased by 70 times.

Direct in situ photolithography of ultra-stable CsPbBr3 quantum dot arrays based on crosslinking polymerization.

CsPbX3 (X = Br, Cl, I) perovskite quantum dots (PQDs) are the rising star for various display applications owing to their excellent opto-electrical properties, such as an adjustable spectrum, narrow emission linewidth and high quantum yield. However, these PQDs are well known to suffer from intrinsic instability under atmospheric conditions. In this work, a novel photosensitive ligand, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (XBPO), was employed as a dual-functional reagent for PQD surface engineering. The XBPO ligand could cleave to produce phenylphosphinyl radicals and trimethylbenzoyl radicals under UV light irradiation. The phenylphosphinyl radicals with PO bonds could effectively passivate the PQD surface defects, leading to quantum yield improvement. The CsPbBr3 and CsPbI3 PQDs with XBPO modification could achieve a photoluminescence quantum yield (PLQY) of near unity and 92%, respectively. Additionally, the in situ encapsulation of the PQDs was achieved by the subsequent crosslinking polymerization, which significantly improved the stability of the PQDs against solvents and the environment. By combining a standard photolithography procedure, we demonstrated a micro-pattern of CsPbBr3 PQDs. These results establish a universal route for PQD patterning, compatible with the existing photolithography processes, which could facilitate the application of PQDs in next-generation display technology.

Stepwise−Process−Controlled Ligand Management Strategy for Efficient and Stable Perovskite Quantum Dot Solar Cells

CsPbI3 perovskite quantum dots (QDs) have attracted much attention in the field of solar cells because of their excellent photovoltaic properties. Conventional modification of long−chain insulating ligands can ensure good dispersion and film−forming stability of QDs, but the limitations of their low defect passivation ability and poor charge transport ability will make them fail to achieve high efficiency in the corresponding solar cell devices. In this study, by introducing “Benzylphosphonic acid” short−chain ligands to the surface of CsPbI3 QDs, the ligands were re−administered on the surface during the preparation of the CsPbI3 QDs as well as during the film−forming process. The strong coordination ability of Benzenephosphonic acid can effectively passivate defects on the surface of CsPbI3 QDs and inhibit non−radiative recombination and phase transition. Meanwhile, this short−chain ligand can effectively promote the charge exchange between adjacent QDs and improve the electrical transport properties of the film. The efficiency of the Benzylphosphonic acid−modified CsPbI3 QDs solar cell reaches 13.91% compared to the unmodified device (PCE of 11.4%). The storage stability and operation stability of the device are also significantly improved. (The efficiency remains at 91% of the original for 800 h of atmospheric storage; the efficiency remains at 92% of the original for 200 h of continuous light exposure.) The present strategy realizes the simultaneous improvement of photovoltaic properties and stability of CsPbI3 QD solar cells and also provides a reference for surface ligand engineering to realize highly efficient and stable perovskite quantum dot solar cells.

Comprehensive guidance for optimizing the colloidal quantum dot (CQD) Perovskite solar cells: experiment and simulation

CsPbI3 perovskite quantum dots (CPQDs) have received great attention due to their potential in large-scale applications. Increasing the efficiency of CPQDs solar cells is an important issue that is addressed in this paper. Here, we have simulated a 14.61% colloidal CPQD solar cell with the least fitting parameter that shows the accuracy of the following results. The absorber layer properties are varied and different power conversion efficiency (PCE) is achieved for the new device. The results show that colloidal CsPbI3 material properties have a significant effect on the PCE of the device. Finally, the optimized parameters for the absorber layer are listed and the optimum efficiency of 29.88% was achieved for this case. Our results are interesting that help the researchers to work on CsPbI3 materials for the achievement of highly efficient, stable, large-scale, and flexible CPQDs solar cells.

Design and Synthesis of Fluorinated Quantum Dots for Efficient and Stable 0D/3D Perovskite Solar Cells

AbstractDimensionality engineering involving the low‐dimensional and 3D perovskites has been demonstrated as an efficient promising strategy to modulate interfacial energy loss as well as instability in perovskite solar cells (PSCs). Herein, the use of fluorinated Cesium Lead Iodide (CsPbI3) perovskite quantum dot (PQD) is first reported as interface modification layer for PSCs. The binding between the CsPbI3 PQD surface and native oleic acid (OLA)/oleylamine (OAm) ligands is governed by a dynamic adsorption–desorption equilibrium. Perfluorooctanoic acid (PFA) with stronger binding affinity and more hydrophobic nature is explored to partially replace OLA to prepare the fluorinated ligand capped CsPbI3 PQDs (F‐CsPbI3). Through optimization of the addition of PFA during hot‐injection synthesis, the in situ treated F‐CsPbI3 PQDs display reduced surface defect states, higher photoluminescence quantum yields together with improved stability. Subsequently, both CsPbI3 and F‐CsPbI3 PQDs are utilized as interface engineering layer in PSCs, delivering the best efficiency values of 21.99% and 23.42%, respectively, which is significantly enhanced compared to the control device (20.37%). More importantly, benefiting from its more hydrophobic properties, the F‐CsPbI3 PQD treated device exhibits excellent ambient storage stability (25 °C, relative humidity: 35–45%), retaining over 80% of its initial efficiency after 1500 h aging.

M13 Bacteriophage-Assisted Synergistic Optical Enhancement of Perovskite Quantum Dots

Bacteriophages demonstrate a remarkable ability to adhere to host surfaces, thus improving their chances of reproduction. These viral entities demonstrate extreme interface properties through their highly specific and periodic peptide receptors, surpassing any manmade surface in terms of variability and adhesiveness. This intriguing quality has led to investigations into biohybrid nanostructures, wherein bacteriophages are combined with inorganic substances. Among them, cesium lead halide (CsPbI3) perovskite quantum dots (PQDs) are promising emissive materials, with their optical characteristics being vital for the advancement of light-emitting and optoelectronic apparatuses. In this study, we explored the integration of M13 bacteriophages (phages) with CsPbI3 PQDs. Our observations indicated that the photoluminescence of CsPbI3 + M13 phage was amplified 7.7-fold compared to pure CsPbI3, the lifetime of the quantum dots extended from 40.47 ns to 53.32 ns and enhanced the stability. Simulations and experimental results both demonstrate the significant role of M13 bacteriophages in achieving enhanced optical properties for PQDs. These findings confirm the significant contribution of M13 phages to enhancing the optical attributes in PQDs, laying the groundwork for innovative optoelectronic applications.

Simultaneous Enhancement of the Luminescence Intensity and Stability of Deep-Red CsPbI3 Perovskite Quantum Dots Achieved by a Doping Strategy.

The phase instability of CsPbI3 perovskite quantum dots (PQDs) restricts their practical applications due to the easy conversion from the luminescent cubic phase to the non-luminescent orthorhombic phase. The elemental doping route has been regarded as one of the most effective strategies to achieve high-quality PQDs-based phosphors. Herein, a stoichiometric amount of nickel chloride (NiCl2) has been effectively doped into the CsPbI3 lattice. The incorporation of Ni2+ ions has little effect on the crystal phase, structure, and morphology of the CsPbI3 PQDs but greatly influences their luminescence properties. The Ni2+ doping not only improves the luminescence performance but also greatly enhances the stability against temperature, storage time, and polar solvent. The formation process and luminescence and stability improvement mechanisms have been discussed. Moreover, the influence of a series of other metal chlorides (KCl, NaCl, MgCl2, ZnCl2, SnCl2, and CaCl2) on the luminescence performance of CsPbI3 PQDs has been systematically investigated, revealing that the luminescence intensity increases by introducing CaCl2, SnCl2, or ZnCl2 but decreases after doping MgCl2, NaCl, or KCl into the CsPbI3 lattice. The as-proposed doping strategy may have a significant impact on tackling the intrinsic instability of all-inorganic CsPbX3 PQDs, shedding light on their future applications in light-emitting diode (LED) devices and solid-state lighting.

Effect of silica encapsulation on the stability and photoluminescence emission of FAxCs1-xPbX3 quantum dots for white mini light emitting diodes

Development of wide-color gamut white light-emitting diodes (WLEDs) for displays, with nitride-based phosphors and conventional core-shell quantum dots (QDs) such as InP, CdSe, and all-inorganic CsPbI3 perovskite quantum dots due to their excellent optoelectronic properties performance, is an excellent candidate for new optoelectronic applications.However, in backlight applications, the color gamut of perovskite quantum dots will be reduced due to the matching degree of color filter, which will limit its application in wide color gamut. To address these issues, in this paper, we propose a novel approach, namely, formamidine acetate (FA+) cationic doping, in CsPbI3 system synthesized at room temperature by organic-inorganic ligand passivation method which can effectively maintain structural stability. At the same time, the PL emission band of CsPbI3 is increased by doping FA + cations and the color gamut range is improved. We will discuss this change in detail, and quantum dot films using spin coating method can be maintained for a month in atmospheric conditions. For practical applications, the color gamut range can reach 133%. Therefore, our proposed perovskite quantum dots, FAxCs1-xPbI3, have great potential for application in wide color gamut displays.

CsPbI3-perovskite quantum dot solar cells: unlocking their potential through improved absorber layer characteristics and reduced defects

Perovskite quantum dots (CsPbI3-PQDs), a translucent material, have gained great interest in the PV industries owing to their unified virtues of perovskites and quantum dots. However, researchers have found that perovskite solar cells (PSCs) suffer from issues like low stability at high relative humidity, energy states imbalance, severe hysteresis, and an easy decomposition under ultraviolet (UV) radiation that severely restrict their industrialization. Quantum dots (QDs) are excellent materials with numerous admirable traits that have been extensively employed in PSCs to overcome the aforementioned problems. To achieve high performance of the examined device, the CsPbI3-PQDs has been stacked between two charge transport layers, i.e., Cl@SnO2 (to facilitate electrons towards cathode) and P3HT (to facilitate holes towards anode). In this context, study of variations in different parameters such as thickness and acceptor density of the CsPbI3-PQDs absorber layer has been done. After varying the thickness and acceptor density of the CsPbI3-PQDs layer, the cell’s performance is optimized at thickness of 400 nm and acceptor density of 1 × 1017/cm3 delivering higher PV parameters power conversion efficiency (PCE):16.17%, open circuit voltage (VOC):1.02 V, short circuit density (JSC):18.06 mA cm−2 and fill factor (FF): 87.06% respectively. Thereafter, the effects of bulk defects in CsPbI3-PQDs and the interface between CsPbI3-PQDs and Cl@SnO2 have been explored in this work. For the cell to work at its best, the bulk defect density and interface defect density, respectively, should not be more than 1 × 1014 /cm3 and 1 × 1013 /cm2. Afterwards, a comprehensive study has been done by varying the front electrode transparency (from 40% to 95%) to improve the device performance. With 95% of front electrode transparency, the performance of device is improved due to increase in the photon coupling.

In Situ Iodide Passivation Toward Efficient CsPbI3 Perovskite Quantum Dot Solar Cells

HighlightsThe introduction of hydroiodic acid (HI) manipulates the dynamic conversion of PbI2 into highly coordinated species to optimize the nucleation and growth kinetics.The addition of HI enables the fabrication of CsPbI3 perovskite quantum dots with reduced defect density, enhanced crystallinity, higher phase purity, and near-unity photoluminescence quantum yield.The efficiency of CsPbI3 perovskite quantum dot solar cells was enhanced from 14.07% to 15.72% together with enhanced storage stability.All-inorganic CsPbI3 quantum dots (QDs) have demonstrated promising potential in photovoltaic (PV) applications. However, these colloidal perovskites are vulnerable to the deterioration of surface trap states, leading to a degradation in efficiency and stability. To address these issues, a facile yet effective strategy of introducing hydroiodic acid (HI) into the synthesis procedure is established to achieve high-quality QDs and devices. Through an in-depth experimental analysis, the introduction of HI was found to convert PbI2 into highly coordinated [PbIm]2−m, enabling control of the nucleation numbers and growth kinetics. Combined optical and structural investigations illustrate that such a synthesis technique is beneficial for achieving enhanced crystallinity and a reduced density of crystallographic defects. Finally, the effect of HI is further reflected on the PV performance. The optimal device demonstrated a significantly improved power conversion efficiency of 15.72% along with enhanced storage stability. This technique illuminates a novel and simple methodology to regulate the formed species during synthesis, shedding light on further understanding solar cell performance, and aiding the design of future novel synthesis protocols for high-performance optoelectronic devices.

Highly Stable CsPbI3 Perovskite Quantum Dots Enabled by Single SiO2 Coating toward Down-Conversion Light-Emitting Diodes

All-inorganic CsPbI3 perovskite quantum dots (PeQDs) have sparked widespread research due to their excellent optoelectronic properties and facile synthesis. However, attaining highly stable CsPbI3 perovskite quantum dots (PeQDs) against heat and polar solvents still remains a challenge and hinders any further practical application. Here, by exploiting (3-aminopropyl) triethoxysilane (APTES) as the sole silica (SiO2) precursor, we report a one-step in situ synthesis of single SiO2-coated CsPbI3 (SiO2-CsPbI3) PeQDs, namely that one SiO2 particle only contains one CsPbI3 PeQD particle. The obtained SiO2-CsPbI3 PeQDs are cubic in shape, have a more uniform size distribution, and possess narrow emission, with near unit photoluminescence quantum yields of up to 97.5%. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy confirm the formation of SiO2 through the hydrolysis of APTES on the CsPbI3 PeQDs surface. Furthermore, they have a significantly improved stability against storage, heat, and ethanol. By combining purple-emission GaN light-emitting diodes, the SiO2-CsPbI3 PeQDs were successfully employed as down-conversion emitters and exhibited considerable enhanced luminous performance and excellent stability, demonstrating their promising future in the practical application of solid-state lighting fields.

Ligand Engineering of CsPbI3 Quantum Dots for Efficient Solar Cells

Perovskite quantum dots (PQDs) have gained significant attention due to their exceptional optical and electronic properties, rendering them promising materials for various optoelectronic applications, such as single-junction solar cells because of the multiple exciton generation effects. To improve the electrical properties of CsPbI3 PQDs, ligand engineering was explored by introducing short-chain ligands to exchange the original long-chain ligands on the PQD surface during the purification process. However, the short-chain ligands suffer from low solubility in the anti-solvent, resulting in insufficient ligand exchange. To address this issue, we developed an in-situ ligand exchange (ILE) strategy to promote the replacement of long-chain ligands with short-chain ones, leading to improved surface chemistry. In this work, 4-methoxyphenethylammonium iodide (CH3O-PEAI) was demonstrated as the short-chain ligand in the ILE strategy, thereby modifying halide vacancy trap states, and promoting carrier transportation and extraction. As a result, the ILE-CsPbI3-based solar cells achieved a higher power conversion efficiency of 14.4% with a high open circuit voltage (VOC) of 1.23 V and exceptional long-term durability due to higher hydrophobicity.

Stabilized Perovskite Quantum Dot Solids via Nonpolar Solvent Dispersible Covalent Ligands.

The ligand exchange procedure of CsPbI3 perovskite quantum dots (PQDs) enables the fabrication of thick and conductive PQD solids that act as a photovoltaic absorber for solution-processed thin-film solar cells. However, the ligand-exchanged CsPbI3 PQD solids suffer from deterioration in photovoltaic performance and ambient stability due to the surface traps, such as uncoordinated Pb2+ sites on the PQD surface, which are generated after the conventional ligand exchange process using ionic short-chain ligands dissolved in polar solvents. Herein, a facile surface stabilization is demonstrated that can simultaneously improve the photovoltaic performance and ambient stability of CsPbI3 PQD photovoltaic absorber using covalent short-chain triphenylphosphine oxide (TPPO) ligands dissolved in a nonpolar solvent. It is found that the TPPO ligand can be covalently bound to uncoordinated Pb2+ sites and the nonpolar solvent octane can completely preserve the PQD surface components. Owing to their synergetic effects, the CsPbI3 PQD photovoltaic absorber stabilized using the TPPO ligand solution dissolved in octane exhibit higher optoelectrical properties and ambient stability than the control absorber. Consequently, CsPbI3 PQD solar cells composed of PQD photovoltaic absorbers fabricated via surface stabilization strategy provide an improved power conversion efficiency of 15.4% and an enhanced device stability.

Efficient semi-transparent perovskite quantum dot photovoltaics enabled by asymmetric dielectric/metal/dielectric transparent electrodes

CsPbI3 perovskite quantum dots (CsPbI3-PQDs) have a high potential as semi-transparent photovoltaic absorbers because of the facile control of film thicknesses, size-tunable optical band gaps, and nanometer-scale grain sizes suppressing light scattering. Conventional semi-transparent CsPbI3-PQD solar cells showed low photovoltaic performances due to the low electrical conductivity of the graphene electrodes. Here we report that dielectric/ultra-thin metal/dielectric (DMD) electrodes with excellent optical transmittance and electrical conductivity deliver superior photovoltaic performances in the semi-transparent CsPbI3-PQD solar cells. Particularly, the asymmetric DMD electrodes composed of MoOx 15 nm/Au 10 nm/MoOx 35 nm (asym-MAM) stacks exhibit higher optical transmittance than that of the symmetric MoOx 15 nm/Au 10 nm/MoOx 15 nm (sym-MAM) stacks. The optical simulation confirms that asym-MAM stacks reduce the parasitic absorption loss in metal interlayers. Therefore, the asym-MAM stacks with a high electrical conductivity show a higher average visible transmittance (AVT) than that of the sym-MAM. Consequently, the semi-transparent CsPbI3-PQD solar cells fabricated using the asym-MAM transparent top electrodes show a power conversion efficiency of 11.3% with a considerable AVT values of 23.4% (400–800 nm) and 20.0% (380–780 nm), respectively, which were calculated from their transmittance spectra. This is the highest-efficiency semi-transparent PQD solar cells that can be used for solar window applications requiring an AVT value of over 20%.

Room-temperature stable CsPbI3 perovskite quantum dots prepared by layer-by-layer assembly for photonic synapse

CsPbX3 (X = I, Br, or Cl) perovskite materials have attracted great interest due to versatile and excellent photoelectric properties, applicable to various devices ranging from memory to solar cells. In particular, the cubic phase of CsPbI3 perovskite has a band gap of 1.73 eV, absorbing most of the visible region. However, despite excellent material properties, it is still difficult to apply to devices due to the unstable crystalline phase of CsPbI3 at room temperature. To overcome this shortcoming, we fabricated a cubic CsPbI3 perovskite quantum dots (CsPbI3-PQDs) thin film using in-situ ligand exchange layer-by-layer self-assembly (LbL SA). These room-temperature stable CsPbI3-PQDs thin films could control not only the thickness in nano-scale, but also the electrical properties. For device application, CsPbI3-PQD was formed on the fluorine doped tin oxide (FTO) substrate by LbL SA method, and W/CsPbI3-PQD/FTO photonic synapse was fabricated and evaluated. This photonic synapse exhibited photo-sensitive current-voltage characteristics under various UV stimuli such as intensity, exposure time, and interval. Furthermore, we successfully emulated the essential synaptic behaviors induced by photonic stimulus including short term plasticity, long term plasticity, and paired pulse facilitation. The CsPbI3-PQD-based device exhibited resistive switching characteristics with Ron/Roff of 103, stable endurance (103 cycles) and retention time (∼ 9 ×103 s). Additionally, we fabricated a heterojunction CsPbI3-PQD/a-IGZO based synaptic device and improved synaptic behaviors under various visible stimuli by enhancing the maintenance capability of photogenerated charge carriers through energy band engineering.

Photomultiplication‐Type Organic Photodetectors with High EQE‐Bandwidth Product by Introducing a Perovskite Quantum Dot Interlayer

AbstractA photomultiplication (PM)‐type organic photodetector (OPD) that exploits the ionic motion in CsPbI3 perovskite quantum dots (QDs) is demonstrated. The device uses a QD monolayer as a PM‐inducing interlayer and a donor–acceptor bulk heterojunction (BHJ) layer as a photoactive layer. When the device is illuminated, negative ions in the CsPbI3 QD migrate and accumulate near the interface between the QDs and the electrode; these processes induce hole injection from the electrode and yield the PM phenomenon with an external quantum efficiency (EQE) >2000% at a 3 V applied bias. It is confirmed that the ionic motion of the CsPbI3 QDs can induce a shift in the work function of the QD/electrode interface and that the dynamics of ionic motion determines the response speed of the device. The PM OPD showed a large EQE‐bandwidth product >106 Hz with a −3 dB frequency of 125 kHz at 3 V, which is one of the highest response speeds reported for a PM OPD. The PM‐inducing strategy that exploits ionic motion of the interlayer is a potential approach to achieving high‐efficiency PM OPDs.

Perovskite QD based paper microfluidic device for simultaneous detection of lung cancer biomarkers – Carcinoembryonic antigen and neuron specific enolase

This work reports the microfabricated paper based analytical device (mPADs) for fluorometric detection of lung cancer biomarkers Carcinoembryonic antigen (CEA) and Neuron specific enolase (NSE) simultaneously. The device is patterned by wax printing on the paper that features two closed circular assay zone, connected to one sample zone through the grooved microfluidic channels for analyte flow. CsPbI3 perovskite quantum dots (IPQDs) were phase engineered (PE) for the first time to make it compatible in aqueous and biological medium. As a proof of concept, these PE- IPQDs along with PE CsPbBr3 perovskite quantum dots (BPQDS) were surface modified with streptavidin and conjugated to specific antibodies for demonstration of multiplexing, via sandwich type immunoassay. In addition to offering benefits of being less expensive, portable, enabling robust and facile operations, these developed mPADs exhibit specific and simultaneous detection of CEA and NSE lung cancer biomarkers. A linear response with a detection limit 0.095 ng/mL and 30.0 ng/mL was achieved for CEA and NSE respectively and while it was 0.12 ng/mL and 32 ng/mL for simultaneous detection. This mPAD device (with negligible toxicity of the probe) thus combines the high-throughput capabilities of a microfluidic network with the high sensitivity and multicolour imaging ability offered by perovskite QDs. This can become a promising diagnostic tool if extended for detection of other proteins or biomarkers involved in environmental and food safety research.