Dimensionality Engineering of Lead Organic Chalcogenide Semiconductors.

Two-dimensional (2D) metal organic chalcogenides (MOCs) such as silver phenylselenolate (AgSePh) have emerged as a new class of 2D materials due to their unique optical properties. However, these materials typically exhibit large band gaps, and their elemental and structural versatility remain significantly limited. In this work, we synthesize a new family of 2D lead organic chalcogenide (LOC) materials with excellent structural and dimensionality tunability by designing the bonding ability of the organic molecules and the stereochemical activity of the Pb lone pair. The introduction of electron-donating substituents on the benzenethiol ligands results in a series of LOCs that transition from 1D to 2D, featuring reduced band gaps (down to 1.7 eV), broadband emission, and strong electron-phonon coupling. We demonstrated a prototypical single crystal photodetector with 2D LOC that showed the dimensionality engineering on the transport property of LOC semiconductors. This study paves the way for further development of the synthesis and optical properties of novel organic-inorganic hybrid 2D materials.

Two-Dimensional Halide Pb-Perovskite-Double Perovskite Epitaxial Heterostructures.

Epitaxial heterostructures of two-dimensional (2D) halide perovskites offer a new platform for studying intriguing structural, optical, and electronic properties. However, difficulties with the stability of Pb- and Sn-based heterostructures have repeatedly slowed the progress. Recently, Pb-free halide double perovskites are gaining a lot of attention due to their superior stability and greater chemical diversity, but they have not been successfully incorporated into epitaxial heterostructures for further investigation. Here, we report epitaxial core-shell heterostructures via growing Pb-free double perovskites (involving combinations of Ag(I)-Bi(III), Ag-Sb, Ag-In, Na-Bi, Na-Sb, and Na-In) around Pb perovskite 2D crystals. Distinct from Pb-Pb and Pb-Sn perovskite heterostructures, growths of the Pb-free shell at 45° on the (100) surface of the lead perovskite core are observed in all Pb-free cases. The in-depth structural analysis carried out with electron diffraction unequivocally demonstrates the growth of the Pb-free shell along the [110] direction of the Pb perovskite, which is likely due to the relatively lower surface energy of the (110) surface. Furthermore, an investigation of anionic interdiffusion across heterostructure interfaces under the influence of heat was carried out. Interestingly, halide anion diffusion in the Pb-free 2D perovskites is found to be significantly suppressed as compared to Pb-based 2D perovskites. The great structural tunability and excellent stability of Pb-free perovskite heterostructures may find uses in electronic and optoelectronic devices in the near future.

3D Printing of Robust High-Performance Conducting Polymer Hydrogel-Based Electrical Bioadhesive Interface for Soft Bioelectronics.

Electrical bioadhesive interface (EBI), especially conducting polymer hydrogel (CPH)-based EBI, exhibits promising potential applications in various fields, including biomedical devices, neural interfaces, and wearable devices. However, current fabrication techniques of CPH-based EBI mostly focus on conventional methods such as direct casting, injection, and molding, which remains a lingering challenge for further pushing them toward customized practical bioelectronic applications and commercialization. Herein, 3D printable high-performance CPH-based EBI precursor inks are developed through composite engineering of PEDOT:PSS and adhesive ionic macromolecular dopants within tough hydrogel matrices (PVA). Such inks allow the facile fabrication of high-resolution and programmable patterned EBI through 3D printing. Upon successive freeze-thawing, the as-printed PEDOT:PSS-based EBI simultaneously exhibits high conductivity of 1.2 S m-1 , low interfacial impedance of 20 Ω, high stretchability of 349%, superior toughness of 109 kJ m-3 , and satisfactory adhesion to various materials. Enabled by these advantageous properties and excellent printability, the facile and continuous manufacturing of EBI-based skin electrodes is further demonstrated via 3D printing, and the fabricated electrodes display excellent ECG and EMG signal recording capability superior to commercial products. This work may provide a new avenue for rational design and fabrication of next-generation EBI for soft bioelectronics, further advancing seamless human-machine integration.

Improved highly efficient Dion-Jacobson type perovskite light-emitting diodes by effective surface polarization architecture.

Quasi-two-dimensional (quasi-2D) perovskites are emerging as promising materials for highly stable light-emitting diodes (LEDs). However, their lower charge transport mobilities and higher defect densities may constrain their light-emitting efficiency. Here, we combine an excessive-salt-assisted (ESA) process with antisolvent treatments to inhibit the defects in Dion-Jacobson-type perovskite LEDs. Such a method could improve the film quality and recombination efficiency. By further investigation, we found that artificially building a bulk junction interface and enhancing surface polarization could play a more important role in promoting the ability of charge carrier injection and recombination for high-performance LED devices. Accordingly, the DJ-type quasi-2D perovskite LED can achieve a high external quantum efficiency (EQE) of 7.1%.

Synthesis of Lead-Free Cs2AgBiX6 (X = Cl, Br, I) Double Perovskite Nanoplatelets and Their Application in CO2 Photocatalytic Reduction.

Morphology control represents an important strategy for the development of functional nanomaterials and has yet to be achieved in the case of promising lead-free double perovskite materials so far. In this work, high-quality Cs2AgBiX6 (X = Cl, Br, I) two-dimensional nanoplatelets were synthesized through a newly developed synthetic procedure. By analyzing the optical, morphological, and structural evolutions of the samples during synthesis, we elucidated that the growth mechanism of lead-free double perovskite nanoplatelets followed a lateral growth process from mono-octahedral-layer (half-unit-cell in thickness) cluster-based nanosheets to multilayer (three to four unit cells in thickness) nanoplatelets. Furthermore, we demonstrated that Cs2AgBiBr6 nanoplatelets possess a better performance in photocatalytic CO2 reduction compared with their nanocube counterpart. Our work demonstrates the first example with two-dimensional morphology of this important class of lead-free perovskite materials, shedding light on the synthetic manipulation and the application integration of such promising materials.

Lead-Free Cs4CuSb2Cl12 Layered Double Perovskite Nanocrystals.

Concerns about the toxicity of lead-based perovskites have aroused great interest for the development of alternative lead-free perovskite-type materials. Recently, theoretical calculations predict that Pb2+ cations can be substituted by a combination of Cu2+ and Sb3+ cations to form a vacancy-ordered layered double perovskite structure with superior optoelectronic properties. However, accessibilities to this class of perovskite-type materials remain inadequate, hindering their practical implementations in various applications. Here, we report the first colloidal synthesis of Cs4CuSb2Cl12 perovskite-type nanocrystals (NCs). The resulting NCs exhibit a layered double perovskite structure with ordered vacancies and a direct band gap of 1.79 eV. A composition-structure-property relationship has been established by investigating a series of Cs4CuxAg2-2xSb2Cl12 perovskite-type NCs (0 ≤ x ≤ 1). The composition induced crystal structure transformation, and thus, the electronic band gap evolution has been explored by experimental observations and further confirmed by theoretical calculations. Taking advantage of both the unique electronic structure and solution processability, we demonstrate that the Cs4CuSb2Cl12 NCs can be solution-processed as high-speed photodetectors with ultrafast photoresponse and narrow bandwidth. We anticipate that our study will prompt future research to design and fabricate novel and high-performance lead-free perovskite-type NCs for a range of applications.

Stereoselective C-C Oxidative Coupling Reactions Photocatalyzed by Zwitterionic Ligand Capped CsPbBr3 Perovskite Quantum Dots.

Semiconductor quantum dots (QDs) have attracted tremendous attention in the field of photocatalysis, owing to their superior optoelectronic properties for photocatalytic reactions, including high absorption coefficients and long photogenerated carrier lifetimes. Herein, by choosing 2-(3,4-dimethoxyphenyl)-3-oxobutanenitrile as a model substrate, we demonstrate that the stereoselective (>99 %) C-C oxidative coupling reaction can be realized with a high product yield (99 %) using zwitterionic ligand capped CsPbBr3 perovskite QDs under visible light illumination. The reaction can be generalized to different starting materials with various substituents on the phenyl ring and varied functional moieties, producing stereoselective dl-isomers. A radical mediated reaction pathway has been proposed. Our study provides a new way of stereoselective C-C oxidative coupling via a photocatalytic means using specially designed perovskite QDs.

Effect of surface recombination in high performance white-light CH3NH3PbI3 single crystal photodetectors.

Methylammonium lead iodide (CH3NH3PbI3), with the organic-inorganic hybrid perovskite (OIHP) structure, has gained tremendous research interest due to its excellent photo-electron conversion ability in the application of photovoltaics. Despite its solution processed polycrystalline thin film form in solar cells, the single crystalline counterpart may offer some incredibly novel optoelectronic functionalities. In this work, a sizable (>5 mm) and high quality CH3NH3PbI3 single crystal has been synthesized by the inverse temperature crystallization method, and a white-light photodetector of the structure glass/ITO/Ga/ CH3NH3PbI3/Au was fabricated. Overbroad photo-excitation intensities ranging from 0.1 mW/cm2 to 100 mW/cm2 using a sun-light simulator, the on-off ratio is tunable in a wide-range from 65 to 2250 at zero bias voltage. The responsivity (R) and detectivity (D*) are 36.2 mA/W and 2.68×1011 Jones respectively at a weak white-light intensity such as 0.1 mW/cm2. Both the photodetective parameters decrease with the increase of the illumination intensity. Based on impedance spectra obtained at working condition and light intensity dependent Jsc measurements, the surface trap-assist recombination may play a dominating role. The corresponding lifetime (τsurf) and resistance (Rsurf_trap) exhibit fast decays at higher illumination intensities. This fundamental study may pave the way for exploring the contribution of the surface trap-assist recombination in the CH3NH3PbI3 single crystal based photodetector. We believe it is applicable for integration in micro-photonics for sensitive and weak white-light photo-detection.

The effects of semantic congruency: a research of audiovisual P300-speller.

BACKGROUND: Over the past few decades, there have been many studies of aspects of brain-computer interface (BCI). Of particular interests are event-related potential (ERP)-based BCI spellers that aim at helping mental typewriting. Nowadays, audiovisual unimodal stimuli based BCI systems have attracted much attention from researchers, and most of the existing studies of audiovisual BCIs were based on semantic incongruent stimuli paradigm. However, no related studies had reported that whether there is difference of system performance or participant comfort between BCI based on semantic congruent paradigm and that based on semantic incongruent paradigm. METHODS: The goal of this study was to investigate the effects of semantic congruency in system performance and participant comfort in audiovisual BCI. Two audiovisual paradigms (semantic congruent and incongruent) were adopted, and 11 healthy subjects participated in the experiment. High-density electrical mapping of ERPs and behavioral data were measured for the two stimuli paradigms. RESULTS: The behavioral data indicated no significant difference between congruent and incongruent paradigms for offline classification accuracy. Nevertheless, eight of the 11 participants reported their priority to semantic congruent experiment, two reported no difference between the two conditions, and only one preferred the semantic incongruent paradigm. Besides, the result indicted that higher amplitude of ERP was found in incongruent stimuli based paradigm. CONCLUSIONS: In a word, semantic congruent paradigm had a better participant comfort, and maintained the same recognition rate as incongruent paradigm. Furthermore, our study suggested that the paradigm design of spellers must take both system performance and user experience into consideration rather than merely pursuing a larger ERP response.

Mental Health Status and Coping Behaviors of the Guangxi Baiku Yao Population in Response to Life Events.

BACKGROUND Ethnic minorities present specific mental health characteristics that are based on their unique cultural background. We aimed to investigate the mental health status and coping behaviors in the Guangxi Baiku Yao population, an ethnic minority in China. MATERIAL AND METHODS A total of 121 Baiku Yao, 149 Zhuang, and 141 Han from Nandan Guangxi were enrolled in a survey using stratified random cluster sampling. The questionnaires included general information, a simplified mental symptom checklist, life events, coping behaviors, and social support. RESULTS The number of stimulating life events in Baiku Yao, particularly in males, was higher than that in the other two groups. Anxiety, depression, and mental symptom scores in Baiku Yao were higher than those in the other two groups. After adjusting for demographic variables, variation in mental health that could be explained by negative coping and life events increased by 40.5% and 7.6%, respectively. All path coefficients were significant (P<0.01); the ratio of the fitting value and the degree of freedom was 1.496, and the root mean square error of approximation was 0.035. CONCLUSIONS Mental symptoms of the Baiku Yao population in Nandan (Guangxi) were more severe than those in other Chinese ethnic groups. Life events affected mental symptoms through negative coping.

[Research on vigilance detection based on pulse wave].

This paper studied the rule for the change of vigilance based on pulse wave. 10 participants were recruited in a 95-minute Mackworth clock test (MCT) experiment. During the experiment, the vigilance of all participants were evaluated by Karolinska sleepiness scale (KSS) and Stanford sleepiness scale (SSS), and behavior data (the reaction time and the accuracy of target) and pulse wave signal of the participants were recorded simultaneously. The result indicated that vigilance of the participants can be divided into 3 classes: the first 30 minutes for high vigilance level, the middle 30 minutes for general vigilance level, and the last 30 minutes for low vigilance level. Besides, time domain features such as amplitude of secondary peak, amplitude of peak and the latency of secondary peak decreased with the decrease of vigilance, while the amplitude of troughs increased. In terms of frequency domain features, the energy of 4 frequency band including 8.600 ~ 9.375 Hz, 11.720 ~ 12.500 Hz, 38.280 ~ 39.060 Hz and 39.060 ~ 39.840 Hz decreased with the decrease of vigilance. Finally, under the recognition model established by the 8 characteristics mentioned above, the average accuracy of three-classification results over the 10 participants was as high as 88.7%. The results of this study confirmed the feasibility of pulse wave in the evaluation of vigilance, and provided a new way for the real-time monitoring of vigilance.

Graphene Oxide Catalyzed C-H Bond Activation: The Importance of Oxygen Functional Groups for Biaryl Construction.

A heterogeneous, inexpensive, and environmentally friendly graphene oxide catalytic system for the C-H bond arylation of benzene enables the formation of biaryl compounds in the presence of aryl iodides. The oxygen functional groups in these graphene oxide sheets and the addition of KOtBu are essential for the observed catalytic activity. Reactions with various model compounds and DFT calculations confirmed that these negatively charged oxygen atoms promote the overall transformation by stabilizing and activating K(+) ions, which in turns facilitates the activation of the C-I bond. However, the graphene π system also greatly facilitates the overall reaction as the aromatic coupling partners are easily adsorbed.

Quantitative comparison of transient elastography (TE), shear wave elastography (SWE) and liver biopsy results of patients with chronic liver disease.

[Purpose] The purpose of this study was to carry out a comparitive analysis of hepatic fibrosis results of the liver hardness of patients with chronic liver disease as measured by elastography (TE), shear wave elastography (SWE), and liver biopsy. [Subjects and Methods] This study was a retrospective analysis of 304 patients who underwent SWE and TE before and after liver biopsy, taken from among patients who had been checked for liver fibrosis by liver biopsy between August 2013 and August 2014. We used receiver operating characteristic (ROC) curve to prove the diagnostic significance of liver stiffness, and then analyzed the sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of SWE and TE, as well as the kappa index through cross-analysis of SWE, TE, and liver biopsy. [Results] For liver hardness, the sensitivity of SWE was 84.39%, the specificity of SWE was 97.92%, the accuracy of SWE was 87.33%, the positive predictive value of SWE was 99.32%, and the negative predictive value of SWE was 63.51%. The sensitivity of TE was 94.80%, the specificity of TE was 77.08%, the accuracy of TE was 90.95%, the positive predictive value of TE was 93.97%, and the negative predictive value of TE was 80.43%. [Conclusion] It is our opinion that SWE and TE are non-invasive methods that are more effective than the invasive methods used for diagnosing liver hardness. Invasive methods cover only a section of liver tissue, and are more likely to cause side effects during biopsy.

Correlations between female breast density and biochemical markers.

[Purpose] The aim of this study was to identify biochemical markers related to breast density. The study was performed with 200 patients who received mammography and biochemical marker testing between March 1, 2014 to October 1, 2014. [Subjects and Methods] Following the American College of Radiology, Breast Imaging Reporting and Data System (ACR BI-RADS), breast parenchymal pattern density from mammography was categorized into four grades: grade 1, almost entirely fat; grade 2, fibroglandular densities; grade 3, heterogeneously dense; and grade 4, extremely dense. Regarding biochemical markers, subjects underwent blood and urine tests after a 12-h fast. We analyzed correlations among breast density, general characteristics, and biochemical markers. [Results] Breast density-related factors were age, height, weight, body mass index (BMI), hematocrit, MCH, RDW, AST, ALT, ALP, uric acid, γGT, triglycerides, total cholesterol, HDL-cholesterol, and LDL-cholesterol. [Conclusion] The results can be used as basic and comparative data for the prevention and early control of breast cancer.

Analysis of enlarged images using time-of-flight magnetic resonance angiography, computed tomography, and conventional angiography.

This study aimed to assess the accuracy of time-of-flight magnetic resonance angiography, computed tomography, and conventional angiography in depicting the actual length of the blood vessels. Three-dimensional time-of-flight magnetic resonance angiography and computed tomography angiography were performed using a flow phantom model that was 2.11 mm in diameter and had a total area of 0.26 cm(2). After this, volume rendering technique and the maximum intensity projection method as well as two-dimensional digital subtraction angiography and three-dimensional rotational angiography based on conventional angiography were conducted. For three-dimensional time-of-flight magnetic resonance angiography, 8 channel sensitivity encoding (SENSE) head coil for the 3.0 Tesla equipment was used. Fluid was added to the normal saline solution at various rates, such as 11.4, 20.0, 31.4, 40.0, 51.5, 60.0, 71.5, 80.1, 91.5, and 100.1 cm/s using an automatic contrast media injector. Each image was thoroughly examined. After reconstructing the image using the maximum intensity projection method, the length of the conduit in the center of the coronal plane was measured 30 times. After performing computed tomography angiography with the 64-channel CT scanner and 16-channel CT scanner, the images were sent to TeraRecon. Then, the length of the conduit in the center of the coronal plane of each image was measured 30 times after reconstructing the images using volume rendering and maximum intensity projection techniques. For conventional angiography, three-dimensional rotational angiography and two-dimensional digital subtraction angiography were used. Images obtained by three-dimensional rotational angiography were reconstructed and enhanced by 33, 50, and 100 % in the 128 Matrix and the 256 Matrix, respectively on the Xtra Vision workstation. The maximum intensity projection was used for the reconstruction, and the length of the conduit was measured 30 times in the center of the coronal plane of each image. Measurements using the two-dimensional digital subtraction angiography were obtained 30 times in the center of the image. As a result, the lumen length measured by three-dimensional enhanced flow MR angiography images was a minimum of 2.51 ± 0.12 mm when the fluid velocity was 40 cm/s. The images obtained by computed tomography angiography were larger than the actual images obtained by using the test equipment and the reconstruction method. Among the reconstruction methods of three-dimensional rotational angiography, the lumen length in the image reconstructed by 100 % in the 256 matrix was the smallest; 2.76 ± 0.009 mm. In the 128 matrix, as the scope of reconstruction was widened, the length of the vessel was increased by 0.710 units. In the 256 matrix, as the scope of reconstruction was widened, the length of the vessel was decreased by 0.972 units. In two-dimensional digital subtraction angiography, the lumen length in the image was 2.22 ± 0.095 mm. Although this image was magnified similar to the image reconstructed by 100 % in the 256 matrix of three-dimensional rotational angiography (P < 0.05), it was closest to the actual image among the images compared in this study. In conclusion, images obtained by two-dimensional digital subtraction angiography were closer to the actual images compared to the images obtained by other procedures. It can be concluded that vascular images obtained by magnetic resonance angiography, CT angiography, and conventional angiography were larger than the actual images.

Molecular templating of layered halide perovskite nanowires.

Layered metal-halide perovskites, or two-dimensional perovskites, can be synthesized in solution, and their optical and electronic properties can be tuned by changing their composition. We report a molecular templating method that restricted crystal growth along all crystallographic directions except for [110] and promoted one-dimensional growth. Our approach is widely applicable to synthesize a range of high-quality layered perovskite nanowires with large aspect ratios and tunable organic-inorganic chemical compositions. These nanowires form exceptionally well-defined and flexible cavities that exhibited a wide range of unusual optical properties beyond those of conventional perovskite nanowires. We observed anisotropic emission polarization, low-loss waveguiding (below 3 decibels per millimeter), and efficient low-threshold light amplification (below 20 microjoules per square centimeter).

Design of adhesive conducting PEDOT-MeOH:PSS/PDA neural interface via electropolymerization for ultrasmall implantable neural microelectrodes.

Conducting polymers are emerging as promising neural interfaces towards diverse applications such as deep brain stimulation due to their superior biocompatibility, electrical, and mechanical properties. However, existing conducting polymer-based neural interfaces still suffer from several challenges and limitations such as complex preparation procedures, weak interfacial adhesion, poor long-term fidelity and stability, and expensive microfabrication, significantly hindering their broad practical applications and marketization. Herein, we develop an adhesive and long-term stable conducting polymer neural interface by a simple two-step electropolymerization methodology, namely, the pre-polymerization of polydopamine (PDA) as an adhesive thin layer followed by electropolymerization of hydroxymethylated 3,4-ethylenedioxythiophene (EDOT-MeOH) with polystyrene sulfonate (PSS) to form stable interpenetrating PEDOT-MeOH:PSS/PDA networks. As-prepared PEDOT-MeOH:PSS/PDA interface exhibits remarkably improved interfacial adhesion against metallic electrodes, showing 93% area retention against vigorous sonication for 20 min, which is one of the best tenacious conducting polymer interfaces so far. Enabled by the simple methodology, we can facilely fabricate the PEDOT-MeOH:PSS/PDA interface onto ultrasmall Pt-Ir wire microelectrodes (diameter: 10 µm). The modified microelectrodes display two orders of magnitude lower impedance than commercial products, and also superior long-term stability to previous reports with high charge injection capacity retention up to 99.5% upon 10,000,000 biphasic input pulse cycles. With these findings, such a simple methodology, together with the fabricated high-performance and stable neural interface, can potentially provide a powerful tool for both advanced neuroscience researches and cutting-edge clinical applications like brain-controlled intelligence.

One-Step Solution Patterning for Two-Dimensional Perovskite Nanoplate Arrays.

Two-dimensional perovskite crystals have attracted significant attention for their diverse optoelectronic characteristics, owing to their superior semiconducting properties. However, the majority of studies to date have focused on single crystals, which pose challenges for integration into device arrays due to their incompatibility with selective growth or conventional lithography techniques. Here, a facile one-step solution process for synthesizing 2D perovskite crystal arrays is proposed through meniscus-guided coating on patterned substrates. We further utilized this method for the synthesis of lateral heterostructure nanoplate arrays. Six different 2D perovskite nanoplate arrays, including epitaxial heterostructures, are successfully realized. Optical and crystallographic characterizations show the high optical performance and crystallinity of the nanoplates. Moreover, this method is further employed to prepare high-performance 2D perovskite nanoplate photosensor arrays. This strategy can be utilized as a guideline for the fundamental investigation of optical properties and the development of high-performance optoelectronics of perovskite materials including photosensors and displays.

Flexible Supercapacitors Based on Stretchable Conducting Polymer Electrodes.

Supercapacitors are widely used in various fields due to their high power density, fast charging and discharging speeds, and long service life. However, with the increasing demand for flexible electronics, integrated supercapacitors in devices are also facing more challenges, such as extensibility, bending stability, and operability. Despite many reports on stretchable supercapacitors, challenges still exist in their preparation process, which involves multiple steps. Therefore, we prepared stretchable conducting polymer electrodes by depositing thiophene and 3-methylthiophene on patterned 304 stainless steel (SS 304) through electropolymerization. The cycling stability of the prepared stretchable electrodes could be further improved by protecting them with poly(vinyl alcohol)/sulfuric acid (PVA/H2SO4) gel electrolyte. Specifically, the mechanical stability of the polythiophene (PTh) electrode was improved by 2.5%, and the stability of the poly(3-methylthiophene (P3MeT) electrode was improved by 7.0%. As a result, the assembled flexible supercapacitors maintained 93% of their stability even after 10,000 cycles of strain at 100%, which indicates potential applications in flexible electronics.

Holistic energy landscape management in 2D/3D heterojunction via molecular engineering for efficient perovskite solar cells.

Constructing two-dimensional (2D) perovskite atop of 3D with energy landscape management is still a challenge in perovskite photovoltaics. Here, we report a strategy through designing a series of π-conjugated organic cations to construct stable 2D perovskites and to realize delicate energy level tunability at 2D/3D heterojunctions. As a result, the hole transfer energy barriers can be reduced both at heterojunctions and within 2D structures, and the preferable work function shift reduces charge accumulation at interface. Leveraging these insights and also benefitted from the superior interface contact between conjugated cations and poly(triarylamine) (PTAA) hole transporting layer, a solar cell with power conversion efficiency of 24.6% has been achieved, which is the highest among PTAA-based n-i-p devices to the best of our knowledge. The devices exhibit greatly enhanced stability and reproducibility. This approach is generic to several hole transporting materials, offering opportunities to realize high efficiency without using the unstable Spiro-OMeTAD.