In order to induce greater light absorption, nano-patterning is often applied to the metal-oxide buffer layer in inverted bulk-heterojunction(BHJ) solar cells. However, current homogeneity was ...significantly disturbed at the interface, leading to an efficiency that was not fully optimized. In this work, an additional PC61BM layer was inserted between the ZnO ripple and the photoactive layer to enhance the electron extraction. The insertion of additional PC61BM layer provided substantial advantages in the operation of inverted BHJ solar cells; specifically, it enhanced current homogeneity and lowered accumulation and trapping of photogenerated charges at the ZnO interface. Inclusion of the additional PC61BM layer led to effective quenching of electron-hole recombination by a reduction in the number of accumulated charges at the surface of ZnO ripples. This resulted in a 16% increase in the efficiency of inverted BHJ solar cells to 7.7%, compared to solar cells without the additional PC61BM layer.
Organic photovoltaics (OPVs) with nonfullerene acceptors (NFAs) feature excellent device performance and device stability. However, they are facing problems when the amine‐rich polyelectrolytes are ...used as cathode interfacial layers. In this work, a small molecule, ethanedithiol (EDT) at the polyethyleneimine ethoxylated (PEIE)/active layer interface is inserted for mitigating the undesirable reaction between amine‐rich groups and electron‐acceptor moieties in NFA. The main role of EDT is to passivate the PEIE surface and prevent electron flow to NFA and the unwanted reaction can be mitigated. It improves the performance of OPV devices by reducing the work function, decreasing trap‐assisted recombination, and improving electron‐mobility. As a result, the flexible device with the PEIE interfacial layer with a power conversion efficiency (PCE) of 7.20% can be improved to 10.11% after the inclusion of EDT. Moreover, EDT‐modified device can retain 98.18% after it is bent for 200 cycles and can maintain 80.83% of its initial PCE under continuous light illuminated in ambient conditions without any encapsulation. Based on these findings, the proposed strategy constitutes a crucial step toward highly efficient flexible OPVs.
High‐performance nonfullerene‐based flexible organic solar cells are achieved by the small‐molecule‐driven interfacial modification. It can prevent the undesirable chemical reaction between polyelectrolyte‐based interfacial layer and photoactive layer by controlling electron flow direction. This strategy can be used regardless of the type of nonfullerene acceptors in flexible organic photovoltaic technology.
Abstract
Solution-processed flexible organic optoelectronic devices have great potential as low-cost organic photovoltaics for energy harvesting, and in organic light-emitting diodes as a lighting ...source. However, a major challenge for improving device performance and stability is the different interfacial characteristics of the hydrophobic organic layers and hydrophilic transparent electrodes, particularly for flexible devices. Surface wetting controlled interfacial engineering can provide a useful method to develop highly efficient flexible organic devices. Here, an unsaturated fatty acid-modified ethoxylated polyethyleneimine organic interfacial layer is designed, which is hydrophobic or hydrophilic on different interfaces. This interlayer results in a power conversion efficiency of 10.57% for rigid and 9.04% for flexible photovoltaic devices. Furthermore, the long-term air storage stability for 250 h is substantially improved, retaining 87.75% efficiency without encapsulation, due to the wettability driven improvement of the optical and electronic properties of the cathode interfacial layer. The performance of organic light emitting diodes also benefitted from the interlayer. This study provides a strategy to simultaneously improve efficiency and stability by controlling the wettability of the interfacial layer.
Poly-Si-based solar cells, prepared via conventional Si processes including phosphoryl chloride(POCl3) doping and diffusion, were investigated in this study in terms of their electrical and optical ...properties, including open-circuit voltage (Voc), short-circuit current (Isc), fill factor, external quantum efficiency and efficiency, employing a few recognized test methods. Also, we compared the experiment results from an identical specimen via Kelvin force microscopy (KFM) and photoconductive atomic force microscopy (PC-AFM), respectively, verifying that the scanning probe technique is very effective both in photovoltaic effect measurement and mechanism establishment. When the results of both conventional and nano-probing techniques are compared, the behavior of the surface potential property is similar to the Voc, and that of the photoinduced current property is similar to the Isc. Through this study, we have demonstrated that the KFM and the PC-AFM are effective tools to monitor and evaluate the properties of solar energy–producing materials and devices.
•Silicon solar cells were fabricated and studied by conventional characterization methods.•Characterization of photovoltaic effect and mechanism was performed using scanning probe microscopy.•Kelvin force microscopy (KFM) and photoconductive atomic force microscopy (PC-AFM) were used.•Behavior of KFM result is similar to Voc, and that of PC-AFM is similar to Isc.•KFM and PC-AFM are effective tools to evaluate solar energy materials.
Indoor organic photovoltaics (IOPVs) have attained considerable research attention as a power source for a low-power consumption self-sustainable electronic device for Internet of Things (IoT) ...applications. This study aims to develop an efficient cathode interfacial layer (CIL) based on a polyethyleneimine (PEIE) derivative, processed at room temperature, for the advancement of non-fullerene acceptor (NFA)-based IOPVs. Using a simple chemical reaction between polyethyleneimine and cobalt (II) chloride, we developed a 3D network-structured CIL. Through quaternary ammonium salts and chelating, metal ions act as mediators and induce metal-ion doping. An inverted device architecture with wide-bandgap and low-bandgap photo-absorber layer is utilized to understand the role of CILs under standard 1 sun and low-light or indoor light illuminations. The IOPV devices with modified CIL (Co-PEIE) having PBDB-T: IT-M and PBDB-T-2F: BTP-4F photo-absorber layers demonstrate a power conversion efficiency of 22.60% and 18.34% under 1000 lux LED lamp (2700 K) illumination conditions, respectively, whereas the IOPV devices with pristine PEIE CIL realized a poor device performance of 18.31% and 14.32% for the PBDB-T: IT-M and PBDB-T-2F: BTP-4F active layers, respectively. The poor device performance of PEIE interlayer-based IOPV under low-light conditions is the result of the significantly high leakage current and low shunt resistance that directly affect the open-circuit voltage (VOC) and fill factor (FF). Therefore, the adjustable energy barrier and notably low leakage current exhibited by the Co-PEIE CIL have a crucial impact on mitigating losses in VOC and FF when operating under low-light conditions.
We developed a method to use NH
2
-functionalized polymer films to align and immobilize DNA molecules on a Si substrate. The plasma-polymerized cyclohexane film was deposited on the Si substrate ...according to the radio frequency plasma-enhanced chemical vapor deposition method using a single molecular precursor, and it was then treated by the dielectric barrier discharge method in a nitrogen environment under atmospheric pressure. Changes in the chemistry of the surface functional groups were studied using X-ray photoelectron spectroscopy and Fourier transformed infrared spectroscopy. The wettability of the surfaces was examined using dynamic contact angle measurements, and the surface morphology was evaluated using atomic force microscopy.
We utilized a tilting method to align λ-DNA molecules that were immobilized by the electrostatic interaction between the amine groups in NH
2
-functionalized polymer films and the phosphate groups in the DNA. The DNA was treated with positively charged gold nanoparticles to make a conductive nanowire that uses the DNA as a template. We observed that the NH
2
-functionalized polymer film was useful for aligning and immobilizing the DNA, and thus the DNA-templated nanowires.
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•We have introduced dynamic etching process.•Conductivity of PEDOT:PSS has improved by dynamic etching process.•Morphology and optical property have been progress.•The performance of ...the device with dynamic etching process was excellent.
The conductivity enhancement of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) by dynamic etching process was investigated to introduce the outstanding and simplest method for soft electronics. Four different samples which were pristine PEDOT:PSS, PEDOT:PSS doped with 5wt.% DMSO, PEDOT:PSS with dipping process, and PEDOT:PSS with dynamic etching process were prepared to compare the properties such as conductivity, morphology, relative atomic percentage, and topography. All samples were characterized by four point probe, current atomic force microscopy (C-AFM), X-ray photoelectron spectroscopy (XPS), and UV–visible spectroscopy. The conductivity of the sample with dynamic etching process showed the highest value as 1299S/cm among four samples. We proved that the dynamic etching process is superior to remove PSS phase from PEDOT:PSS film, to flow strong current through entire surface of PEDOT:PSS, and to show the smoothest surface (RMS 2.28nm). XPS analysis was conducted for accurate chemical and structural surface environments of four samples and the relative atomic percentage of PEDOT in the sample with dynamic etching was the highest as 29.5%. The device performance of the sample with the dynamic etching process was outstanding as 10.31mA/cm2 of Jsc, 0.75eV of Voc, 0.46 of FF, and 3.53% of PCE. All properties and the device performance for PEDOT:PSS film by dynamic etching process were the most excellent among the samples.
The production of hydrogen from water via solar energy conversion has attracted immense attention as a potential solution for addressing energy supply issues. We demonstrated a stable and efficient ...organic-inorganic hybrid photoelectrochemical (H-PEC) cell. Modifying the surface energy and structure of the organic photoactive layer using multi-functional nanomaterials including –OH-modified NiO nanoparticles and reduced graphene oxide (RGO) led to a 2.8-fold enhancement of the water splitting performance in a single junction H-PEC cell. The enhanced performance was attributed to the i) improved water-wettability, ii) enhanced charge extraction property by band-edge alignment, and iii) the catalytic effect of the introduced NiO-OH nanoparticles. In addition, because of the effects of the RGO layer preventing water penetration and photo-corrosion during the oxidation of water, a distinguishable long-term stability was achieved from the H-PEC cell with an RGO capping layer. The best performance was obtained from the organic-inorganic hybrid multi-junction PEC cells consisting of the WO3 photo-anode (activated under UV irradiation) and the H-PEC cell (activated under visible light irradiation). The H-PEC cell with a WO3 photo-anode exhibited significantly enhanced stability and performance by a factor of 11.6 higher than photocurrent of the single H-PEC cell.
Stable photoelectrochemical cells were demonstrated by gradually modifying the surface energy using efficient organic-inorganic hybrid multilayered structure. Display omitted
•Stable organic-inorganic hybrid photoelectrochemical cells were demonstrated.•Distinguishable long-term stability was achieved from the photoelectrochemical cell.•The hybrid photoelectrochemical cell with a WO3 exhibited enhanced stability.
We successfully fabricated a square pattern of anodic alumina oxide (AAO) template in thin Al film grown on Si substrate utilizing focused ion beam (FIB) milled indent. The pore size and its period ...of the square matrix were about 50
nm and 100
nm, respectively. We found that the minimum indented depth is required to satisfy the critical electric field which is a vertical component toward downward. In addition, we found that the anodizing voltage plays an important role in determining the pore shape and uniformity. The higher anodizing voltage not only reduces the minimum indent depth that is required to create a matrix array but also improves the uniformity of pore shapes in the matrix array.
We have employed Kelvin force microscopy (KFM) system to measure the potential change of a single SnO2 nanowire which had been synthesized on the Au thin film by a thermal process. By using the KFM ...probing technique, Rh coated conducting cantilever can approach a single SnO2 nanowire in nano scale and get the potential images with oscillating AC bias between Au electrode and cantilever. Also, during imaging the potential status, we controlled the concentration of oxygen in measuring chamber to change the ionosorption rate. From the results of such experiments, we verified that the surface potential as well as doping type of a single SnO2 nanowire could be changed by oxygen ionosorption. KCI Citation Count: 0
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