In the fabrication of polymeric electroluminescent devices with indium-tin oxide (ITO) as anode, indium contamination of the polymers can greatly degrade the device performance. In the present study, we have used x-ray photoelectron spectroscopy to measure indium incorporation in poly(3,4-ethylene dioxythiophene):poly(styrene sulphonate), referred to as PEDOT:PSS, which were spincast on bare ITO and encapsulated ITO. We found that the deposition of a self-assembled monolayer of alkylsiloxanes on ITO prior to spincasting PEDOT:PSS was effective and practical in blocking the reactions between ITO and PEDOT:PSS.
Organic halide salts are successfully incorporated in perovskite-based planar-heterojunction solar cells as both the processing additive and interfacial modifier to improve the morphology of the perovskite light-absorbing layer and the charge collecting property of the cathode. As a result, perovskite solar cells exhibit a significant improvement in power conversion efficiency (PCE) from 10% of the reference device to 13% of the modified devices.
High-performance see-through power windows, derived from newly designed semitransparent organic solar modules, exhibit excellent energy generation and saving features.
Abstract Low-dimensional metal halide perovskites have emerged as promising alternatives to the traditional three-dimensional (3D) components, due to their greater structural tunability and environmental stability. Dion-Jacobson (DJ) phase two-dimensional (2D) perovskites, which are formed by incorporating bulky organic diammonium cations into inorganic frameworks that comprises a symmetrically layered array, have recently attracted increasing research interest. The structure-property characteristics of DJ phase perovskites endow them with a unique combination of photovoltaic efficiency and stability, which has led to their impressive employment in perovskite solar cells (PSCs). Here, we review the achievements that have been made to date in the exploitation of DJ phase perovskites in photovoltaic applications. We summarize the various ligand designs, optimization strategies and applications of DJ phase PSCs, and examine the current understanding of the mechanisms underlying their functional behavior. Finally, we discuss the remaining bottlenecks and future outlook for these promising materials, and possible development directions of further commercial processes.
Reversible switching characteristics of organic nonvolatile memory transistors (ONVMTs) using chemically synthesized graphene oxide (GO) nanosheets as a charge-trapping layer are reported. The transfer curves of GO based ONVMTs showed large gate bias dependent hysteresis with threshold voltage shifts over 20 V. After writing and erasing, stored data were well maintained showing more than two orders of ON/OFF ratio (ION/IOFF=∼102) for 104 s. These results suggest that GO nanosheets are one potential candidate as the charge-trapping layer in ONVMTs.
Organic solar cells have attracted academic and industrial interests due to the advantages like lightweight, flexibility and roll-to-roll fabrication. Nowadays, 18% power conversion efficiency has been achieved in the state-of-the-art organic solar cells. The recent rapid progress in organic solar cells relies on the continuously emerging new materials, device fabrication technologies, and the deep understanding on film morphology, molecular packing and device physics. Donor and acceptor materials are the key materials for organic solar cells since they determine the device performance. The past 25 years have witnessed an odyssey in developing high-performance donors and acceptors. In this review, we focus on those star materials and milestone work, and introduce the molecular structure evolution of the key materials. These key materials include homopolymer donors, D-A copolymer donors, A-D-A small molecule donors, fullerene acceptors and nonfullerene acceptors. At last, we outlook the challenges and very important directions in key materials development.
The interface of electron-selective ZnO in inverted polymer bulk-heterojunction (BHJ) solar cells was modified with a series of fullerene-based self-assembled monolayers (C60-SAM) containing different anchoring groups (catechol, carboxylic acid, and phosphonic acid), linkage location, and functionalization. The formation of the C60-SAM to the surface of ZnO was investigated by processing the SAM through either a solution immersion technique or a solution spin-coating method. It is found that the C60-SAMs with the carboxylic acid and catechol termination can be formed onto the surface of ZnO by simple solution spin-coating process, whereas all three anchoring groups can be formed by solution immersion technique. Heterojunction devices were fabricated under different processing conditions to form SAM leading to 2-fold, 75%, and 30% efficiency improvement with the carboxylic acid, catechol, and phosphonic acid C60-SAMs, respectively. The main contribution to the variation of efficiency from different SAMs is due to the open circuit voltage affected by different anchoring groups and functionalization of the C60-SAM. The results from BHJ devices show an efficiency enhancement of ∼6−28% compared to devices without SAM modification because of the improved photoinduced charge transfer from polymer to the C60-SAM/ZnO. The SAM formation condition influences the device performance. Because of the strong acidic nature of the phosphonic acid anchoring group, immersing the ZnO substrate into a solution containing the C60-phosphonic acid SAM for an extended period of time will lead to degradation of the ZnO surface. This in turn, leads to devices without any photovoltaic activity, whereas weaker acids like carboxylic acid and catechol-based C60-SAMs can be assembled onto ZnO, leading to devices with average efficiencies of 4.4 and 4.2%, respectively.
Two donor–acceptor polymers (P1 and P2) based on dithienobenzoquinoxaline (M1) and dithienobenzopyridopyrazine (M2) as acceptor and indacenodithiophene as donor were synthesized via Stille polycondensation. The fused dithienobenzene unit in M1 and M2 units can improve the intermolecular stacking of polymer and also decrease the steric hindrance. P1, with dithienobenzoquinoxaline acceptor, shows a band gap of 1.61 eV. The band gap of P2 was reduced to 1.48 eV after changing to dithienobenzopyridopyrazine as the acceptor unit. The mobilities of P1 and P2 reach 5.6 × 10–2 and 1.5 × 10–2 cm2 V–1 s–1, respectively. The results from photovoltaic measurements showed a very promising PCE of 6.06% for the P1/PC71BM blend system without any thermal or solvent treatments, showing a great offer for the roll-to-roll manufacturing of PSCs.
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