Interface modification of perovskite solar cells (PSCs) has been widely explored not only to achieve defect passivation but also to facilitate charge transport and stabilize the physical/electrical ...contact at device interfaces. In this study, 2‐(9H‐carbazol‐9‐yl)ethylphosphonic acid (CEPA) is introduced as an interface modifier at the interface of perovskite and the hole transporting material (HTM) layer into n‐i‐p PSCs. CEPA reduces surface traps, manipulates the surface dipole for energy‐level alignment, and induces molecular interaction at the interface of the CEPA‐HTM for enhanced interfacial adhesion energy and good mechanical stability. The power conversion efficiency of interface‐optimized PSC is 23.6% using a 2D/3D perovskite structure, representing the highest efficiency among poly(triarylamine) HTM‐based devices. The encapsulated CEPA‐treated PSCs maintain nearly 90% of their initial efficiency during a damp heat lasting for more than 1530 h and retain their initial efficiency during continuous operation under illumination.
An interface modifier (IM) that interacts not only with perovskite but also with hole transporting material is introduced for efficient and stable perovskite solar cells. The best solar cell employing rational IM exhibits a power conversion efficiency of 23.6% with a 2D/3D perovskite structure. Thermal and operational stabilities of interface‐optimized devices are demonstrated.
Short-wave infrared (SWIR) emitters are at the center of ground-breaking applications in biomedical imaging, next-generation optoelectronic devices, and optical communications. Colloidal nanocrystals ...based on indium arsenide are some of the most promising SWIR emitters to date. However, the lack of single-particle spectroscopic methods accessible in the SWIR has prevented advances in both nanocrystal synthesis and fundamental characterization of emitters. Here, we demonstrate an implementation of a solution photon correlation Fourier spectroscopy (s-PCFS) experiment utilizing the SWIR sensitivity and time resolution of superconducting nanowire single-photon detectors to extract single-particle emission linewidths from colloidal indium arsenide/cadmium selenide (InAs/CdSe) core/shell nanocrystals emissive from 1.2 to 1.6 μm. We show that the average single InAs/CdSe nanocrystal fluorescence linewidth is, remarkably, as narrow as 52 meV, similar to what has been observed in some of the most narrowband nanostructured emitters in the visible region. Additionally, the single nanocrystal fluorescence linewidth increases with increasing shell thickness, suggesting exciton–phonon coupling as the dominant emission line-broadening mechanism in this system. The development of the SWIR s-PCFS technique has enabled measurements of spectral linewidths of colloidal SWIR-emissive NCs in solution and provides a platform to study the single NC spectral characteristics of SWIR emitters.
Hybrid perovskite solar cells (PSCs) with high average visible transmission (AVT) are applicable to building-integrated photovoltaics (BIPV) and windows. Reducing perovskite thin film thickness is an ...ideal approach that does not require complex processing methods to achieve high AVT. However, it has been challenging to fabricate high quality perovskite film thin enough to achieve the AVT requirement for BIPV applications without compromising overall optoelectronic properties. In this work, we improve the crystallization of perovskite film and enhance interface properties by incorporating a potassium pyrophosphate (KPP) interlayer between the bottom electron transporting layer and the perovskite photoactive layer. This results in superior optoelectronic characteristics in PSCs, with power conversion efficiency (PCE) of up to 16%, at which the AVT can reach up to 36% (measured without opaque metal contacts), while also demonstrating improved long-term stability. To investigate material potential as semi-transparent PSC, 5 cm × 5 cm semi-transparent mini-modules were fabricated; they exhibited PCEs of up to 9.8% at a high AVT of 30%. These modules exhibited high stability under both simulated light and in an outdoor environment, tracked for over 1000 h and 75 days, respectively.
Hybrid perovskite solar cells (PSCs) with high average visible transmission (AVT) are applicable to building-integrated photovoltaics (BIPV) and windows.
Bismuth-based materials have been studied as alternatives to lead-based perovskite materials for photovoltaic applications. However, poor film quality has limited device performance. In this work, we ...developed a solvent-engineering method and show that it is applicable to several bismuth-based compounds. Through this method, we obtained compact films of methylammonium bismuth iodide (MBI), cesium bismuth iodide (CBI), and formamidinium bismuth iodide (FBI). On the basis of film growth theory and experimental analyses, we propose a possible mechanism of film formation. Additionally, we demonstrate that the resultant compact MBI film is more suitable to fabricate efficient and stable photovoltaic devices compared to baseline MBI films with pinholes. We further employed a new hole-transporting material to reduce the valence-band offset with the MBI. The best-performing photovoltaic device exhibits an open-circuit voltage of 0.85 V, fill factor of 73%, and a power conversion efficiency of 0.71%, the highest reported values for MBI-based photovoltaic devices.
Since the first publication by Miyasaka in 2009 on the use of lead halide perovskite as a light-harvesting material (Kojima, A.; Teshima, K.; Shirai, Y.; Miyasaka, T. Organometal Halide Perovskites ...as Visible-Light Sensitizers for Photovoltaic Cells. J. Am. Chem. Soc. 2009, 131, 6050), unprecedented successes have been achieved and great efforts have been made in the field of perovskite solar cells (PSCs) to push the power conversion efficiency (PCE) past 25%, which corresponds to ∼80% of this material’s theoretical bandgap limit determined on the basis of the Shockley–Queisser theory. Recent progress is mainly attributed to the development of key strategies that effectively reduce the defects on the surface of the perovskite layer and minimize non-radiative recombination at the interfaces, thereby enhancing device efficiency. For future development of PSCs with PCEs exceeding 26%, this Perspective highlights an investigation of the key factors that have allowed realization of efficient PSCs with state-of-the-art PCEs and includes a discussion of practical strategies, including full optimization of the electron-transport layer, minimization of defect loss related to non-radiative recombination, and enhancement of light-harvesting near the band-edge.
We report electrochemical detection of collisions between individual magnetic microbeads, present at subattomolar concentrations, and electrode surfaces. This limit of detection is 4 orders of ...magnitude lower than has been reported previously, and it is enabled by using a magnetic field to preconcentrate the microbeads prior to detection in a microfluidic electrochemical cell. Importantly, the frequency of collisions between the microbeads and the electrode is not compromised by the low concentration of microbeads. These findings represent an unusual case of detecting individual electrochemical events at very low analyte concentration. In addition to experiments supporting these claims, finite-element simulations provide additional insights into the nature of the interactions between flowing microbeads and their influence on electrochemical processes.
Rhinophyma is a phenotypic subtype of rosacea affecting the nose. It is characterized by phymatous changes, skin thickening/fibrosis, glandular hyperplasia, and chronic inflammation. Treatment of ...severe rhinophyma is predominantly surgical excision with closure by secondary intention. Amniotic membrane has been used to promote wound healing, fibrosis, and inflammation. In this case study, the authors present a 63-year-old male with longstanding rhinophyma treated with surgical excision with intraoperative placement of amniotic membrane.
Methylammonium lead iodide (MAPI) is a prototypical photoabsorber in perovskite solar cells (PSCs), reaching efficiencies above 20%. However, its hygroscopic nature has prompted the quest for ...water-resistant alternatives. Recent studies have suggested that mixing MAPI with lower dimensional, bulky-A-site-cation perovskites helps mitigate this environmental instability. On the other hand, low dimensional perovskites suffer from poor device performance, which has been suggested to be due to limited out-of-plane charge carrier mobility resulting from structural dimensionality and large binding energy of the charge carriers. To understand the effects of dimensionality on performance, we systematically mixed MA-based 3D perovskites with larger A-site cations to produce dimethylammonium, iso-propylammonium, and
t
-butylammonium lead iodide perovskites. During the shift from MAPI to lower dimensional (LD) PSCs, the efficiency is significantly reduced by 2 orders of magnitude, with short-circuit current densities decreasing from above 20 mA cm
−2
to less than 1 mA cm
−2
. In order to explain this decrease in performance, we studied the charge carrier mobilities of these materials using optical-pump/terahertz-probe, time-resolved microwave photoconductivity, and photoluminescence measurements. The results show that as we add more of the low dimensional perovskites, the mobility decreases, up to a factor of 20 when it reaches pure LD perovskites. In addition, the photoluminescence decay fitting is slightly slower for the mixed perovskites, suggesting some improvement in the recombination dynamics. These findings indicate that changes in structural dimensionality brought about by mixing A-site cations play an important role in determining the measured charge carrier mobility, and in the performance of perovskite solar cells.
Changes in perovskite structural dimensionality brought by mixing A-site cations play an important role in determining the measured charge carrier mobility, and in the solar cell performance.
An integrated microfluidic/magnetophoretic methodology was developed for improving signal response time and detection limits for the chronoamperometric observation of discrete nanoparticle/electrode ...interactions by electrocatalytic amplification. The strategy relied on Pt-decorated iron oxide nanoparticles which exhibit both superparamagnetism and electrocatalytic activity for the oxidation of hydrazine. A wet chemical synthetic approach succeeded in the controlled growth of Pt on the surface of FeO/Fe3O4 core/shell nanocubes, resulting in highly uniform Pt-decorated iron oxide hybrid nanoparticles with good dispersibility in water. The unique mechanism of hybrid nanoparticle formation was investigated by electron microscopy and spectroscopic analysis of isolated nanoparticle intermediates and final products. Discrete hybrid nanoparticle collision events were detected in the presence of hydrazine, an electrochemical indicator probe, using a gold microband electrode integrated into a microfluidic channel. In contrast with related systems, the experimental nanoparticle/electrode collision rate correlates more closely with simple theoretical approximations, primarily due to the accuracy of the nanoparticle tracking analysis method used to quantify nanoparticle concentrations and diffusion coefficients. Further modification of the microfluidic device was made by applying a tightly focused magnetic field to the detection volume to attract the magnetic nanoprobes to the microband working electrode, thereby resulting in a 6-fold increase to the relative frequency of chronoamperometric signals corresponding to discrete nanoparticle impact events.
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