PSS Anode Buffer Layer Research Articles

Water‐Induced Formation of α‐MoO3 Microcrystals as Anode Buffer Layer for Highly Efficient Polymer Solar Cells

Interfacial modification is an effective method to improve the performance of polymer solar cells (PSCs), and molybdenum oxide is one of the most widely used anode buffer layer (ABL) materials in PSCs. However, the complicated preparations with high‐temperature annealing or vacuum deposition make it uneconomic. Herein, a facile method to prepare MoOx solution in 1‐hexanol is proposed, and the component of the product can be simply adjusted by controlling the amount of introduced water. The added water facilitates the generation of α‐MoO3 microcrystals. To the best of our knowledge, this is also the first report to obtain α‐MoO3 through such a simple method. The obtained MoOx solutions are utilized to fabricate ABL in high efficiency PSCs to improve the performance. High temperature treatment is omitted, while the PCEs of binary and ternary devices can be enhanced to 16.09% and 16.81%, respectively, significantly higher than the devices with PEDOT:PSS ABL (15.55% and 15.93%). Herein, an efficient method to prepare MoOx solution in 1‐hexanol with controlled component is offered, and it is demonstrated that the MoOx ABL derived from the MoOx solution is a potential replacement to enhance the performance of high efficiency PSCs.

Spray coated europium doped PEDOT:PSS anode buffer layer for organic solar cell: The role of electric field during deposition

Poly (3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) doped with Eu3+ is spray deposited for creating an Anode buffer layer (ABL). The doping of Eu3+ in PEDOT:PSS causes the down-shifting of the UV light to visible spectrum enhancing the photon concentration in this region. The use of electric field during the spray deposition of undoped and Eu3+ doped PEDOT:PSS film improved the surface morphology and the electrical conductivity, which help to improve the solar cell performance. The organic solar cell (ITO/ABL/PTB7:PC71BM/Al) fabricated using the electric field assisted spray deposited Eu3+ doped PEDOT:PSS ABL is shown improvement in the power conversion efficiency in comparison to the device fabricated using undoped PEDOT:PSS without electric field. This enhancement in the efficiency of the device in terms of current density and Fill factor can be attributed to an increase in the photon concentration in visible region due to the downshifting and improvement in the surface morphology and conductivity due to applied electric field during deposition.

Bright prospect of using alcohol-soluble Nb2O5 as anode buffer layer for efficient polymer solar cells based on fullerene and non-fullerene acceptors

New breakthroughs are expecting to be achieved based on the discovery of novel interfacial materials for polymer solar cells (PSCs). Herein, the simple and facial approach of spin-coating technology with post heat and ultraviolet-ozone treatment is performed on niobium oxalate to prepare Nb2O5 interfacial layer with ultra-high transmittance. The ultraviolet photoemission spectroscopy results confirm that Nb2O5 with a work function of 4.85 eV is suitable for employing as anode buffer layer (ABL). The average power conversion efficiencies (PCEs) of the P3HT:PCBM-based fullerene devices with Nb2O5 ABL reaches to 4.01%, surpassing that (3.69%) of the control devices with ITO/PEDOT:PSS ABL. Further investigations on the PBDB-T:ITIC-based non-fullerene PSCs with Nb2O5 ABL demonstrate that a PCE as high as 8.67% can be reached, which is superior to that of device modified by PEDOT:PSS ABL (8.03%). Namely, 8% efficiency improvement in PSCs based on fullerene and non-fullerene acceptors realized as compared to the control devices with PEDOT:PSS ABL.

Aqueous solution‐processed NiOx anode buffer layers applicable for polymer solar cells

ABSTRACTA green and facile method has been developed for the room temperature and aqueous solution preparation of NiOx film as anode buffer layers for polymer solar cells (PSCs). The NiOx buffer layer is prepared simply by spin‐coating nickel acetylacetonate precursor‐based aqueous solution onto ITO substrate at room temperature in air. UV‐ozone post‐treatment promotes the formation of dipolar NiOOH species on the film surface, resulting in the anode buffer layer with suitable work function. PSCs have been fabricated with the device structure of ITO/NiOx/photoactive layer/PFN/Al. The power conversion efficiencies of the PSCs based on PTB7:PC71BM blends (8.43%) and P3HT:PC71BM blends (3.04%) with NiOx anode buffer layer are comparable to those with the commonly used PEDOT:PSS anode buffer layer. In addition, the devices made with NiOx buffer layer exhibit much better air stability than those with PEDOT:PSS. These results indicate that the water solution processed NiOx film at room temperature in air is a promising anode buffer layer for efficient and stable PSCs. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 747–753

Solution-Processable Cathode Buffer Layer for High-Performance ITO/CuSCN-based Planar Heterojunction Perovskite Solar Cell

Organic-inorganic hybrid perovskite solar cells (pero-SCs) have attracted tremendous attention recently because of their excellent photovoltaic performance. Simultaneously achieving high performance and long-term stability mainly relies on improving the quality of the perovskite film and overcoming the interface losses through interface engineering. Here, we demonstrate a high performance ITO/CuSCN-based planar heterojunction pero-SCs using solution-processable perylene−diimide derivative PDINO as cathode buffer layer. The device showed a high open-circuit voltage (Voc) of 1.05V, a hysteresis-free photovoltaic response and a maximum power conversion efficiency (PCE) of 16.4%. The high performance can be ascribed to the proper choice of the anode and cathode interface materials. In comparison with the commonly used PEDOT:PSS anode buffer layer, the CuSCN anode buffer layer can increase the built-in potential and decrease the interfacial energy barrier with CH3NH3PbI3, which results in higher Voc. The thickness-insensitive PDINO cathode buffer layer is beneficial to higher short circuit current density. The results indicate that the combination of the CuSCN anode buffer layer and PDINO cathode buffer layer is an effective way to get high photovoltaic performance of the p-i-n planar pero-SCs.

Efficient polymer solar cells with polyethylene glycol cathode buffer layer and improved PEDOT:PSS conductivity

By depositing polyethylene glycol (PEG) on the PEDOT:PSS anode buffer layer of polymer solar cells, we find that PEG not only penetrates downward into the PEDOT:PSS film and improves the conductivity of the anode buffer layer, but also migrates upward to the active layer/Al interface, and thereby forming a cathode buffer layer. The double-logarithmic plots of the net photocurrent against the effective applied voltage imply that the phase separation of the active layer formed by PEG migration is beneficial to exciton dissociation. When 4% PEG was deposited on PEDOT:PSS layer, the power conversion efficiency of polymer solar cell increases from 2.69 to 3.88%.

Enhancing mechanical properties of highly efficient polymer solar cells using size-tuned polymer nanoparticles.

The low mechanical durability of polymer solar cells (PSCs) has been considered as one of the critical hurdles for their commercialization. We described a facile and powerful strategy for enhancing the mechanical properties of PSCs while maintaining their high power conversion efficiency (PCE) by using monodispersed polystyrene nanoparticles (PS NPs). We prepared highly monodispersed, size-controlled PS NPs (60, 80, and 100 nm), and used them to modify the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) anode buffer layer (ABL). The PS NPs played two important roles; i.e., they served as (1) binders in the PEDOT:PSS films, and (2) interfacial modifiers between ABL and the active layer, resulting in remarkable improvement of the mechanical integrity of the PSCs. The addition of PS NPs enhanced the inherent mechanical toughness of the PEDOT:PSS ABL due to their elastic properties, allowing the modified ABL to tolerate higher mechanical deformations. In addition, the adhesion energy (Gc) between the active layer and the modified PEDOT:PSS layer was enhanced significantly, i.e., by a factor of more than 1.5. The Gc value has a strong relationship with the sizes of the PS NP, showing the greatest enhancement when the largest size PS NPs (100 nm) were used. In addition, PS NPs significantly improve the air-stability of the PSCs by suppressing moisture adsorption and corrosion of the electrodes. Thus, the modification of ABL with PS NPs effectively enhances both the mechanical and the long-term stabilities of the PSCs without sacrificing their PCE values, demonstrating their great potential as applications in flexible organic electronics.

Inducting effects of ionic liquid crystal modified-PEDOT:PSS on the performance of bulk heterojunction polymer solar cells

Photovoltaic performance was improved in P3HT/PCBM bulk-heterojunction solar cells induced by ionic liquid crystals modified PEDOT:PSS anode buffer layer.

Solution-Processed and Low-Temperature Annealed CrOx as Anode Buffer Layer for Efficient Polymer Solar Cells

A simple but efficient method has been first developed for the solution preparation of CrOx as anode buffer layer for polymer photovoltaic cells. The chromium acetylacetonate precursor can be transformed into CrOx upon thermal annealing at ∼60 °C, followed by ultraviolet-ozone treatment. The leakage current of the device with the CrOx anode buffer layer was decreased, and short-circuit current density (Jsc) was significantly increased in comparison with the device with the traditional poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) buffer layer. By analyzing the current density–voltage characteristics of the device, it is found that the CrOx anode buffer layer can simultaneously decrease the series resistance and increase the parallel resistance of the device, in comparison with the device with PEDOT:PSS anode buffer layer. For the cells based on poly(3-hexylthiophene) (P3HT) as donor and (6,6)-phenyl-C61-butyric acid methyl ester (PCBM) as acceptor, the power conversion efficiency (...

Enhancing the Efficiency of Polymer Solar Cells by Modifying Buffer Layer with N,N-Dimethylacetamide

We modified the PEDOT:PSS anode buffer layer in P3HT:PCBM bulk heterojunction polymer solar cells by spin-coating the solvent N,N-dimethylacetamide (DMAC). This modification significantly enhanced the efficiency of the ITO/PEDOT:PSS/DMAC/P3HT:PCBM/LiF/Al solar cells. The DMAC-treated device spin-coated at 3000 rpm exhibited a power conversion efficiency (PCE) of 3.74%, a 59% improvement over that of an untreated cell. To study the mechanism of improving the conversion efficiency, we characterized many parameters, including the light and darkI-Vcurves, external quantum efficiency, active layer absorption spectrum, transmission spectrum of ITO:PEDOTPSS, PEDOT:PSS surface morphology, and electrical conductivity. Modifying the PEDOT:PSS film increased conductivity, making it more conducive to hole extraction and collection. Our findings suggest that modifying the anode buffer layer can improve photoelectric conversion efficiency.

Extremely stable organic photovoltaic incorporated with WOxdoped PEDOT:PSS anode buffer layer

The state of interfaces between organic semiconductors and/or metals in organic devices severely impacts their performance and stability. The commonly used organic semiconductor PEDOT:PSS (poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)) is hygroscopic in nature and can therefore be easily damaged if exposed to air and/or light illumination. In this study, we doped PEDOT:PSS with WOx nanocrystallites and found that organic photovoltaics (OPVs) with the WOx doped PEDOT:PSS degrade only by 5%, while OPVs with undoped PEDOT:PSS retain only 23% of their initial power conversion efficiency (PCE) after storing for 5000 h in air. Also, doping PEDOT:PSS with WOx enhances the initial PCE by ∼13%, owing to reduced leakage current density and better Ohmic contact between the PEDOT:PSS and the anode.

Enhancement of performance of P3HT：PCBM based polymer solar cell by Ag2O/PEDOT：PSS composite buffer layer

Ag2O/PEDOT:PSS used as the anode buffer layer is introduced into the P3HT:PCBM based polymer solar cell (PSC). Effect of the Ag2O/PEDOT:PSS composite anode buffer layer on the device performance is investigated. According to the results, we can find that the post-thermal annealing can improve the performance of the PSC with Ag2O/PEDOT:PSS anode buffer layer compare with that without buffer layer. In addition, compared with the devices without such a buffer layer or with only PEDOT:PSS buffer layer, the device with the composite buffer layer can achieve higher Jsc, external quantum efficiency as well as power conversion efficiency. We conclude that the post-thermal annealing can significantly improve the surface morphology which increases the light absorption and the exciton dissociation. The inserted Ag2O together with PEDOT:PSS as the composite buffer layer not only efficiently lowers the hole extraction barrier and improves the hole collection efficiency but also exhibits excellent stability.

Low-temperature MoO3film from a facile synthetic route for an efficient anode interfacial layer in organic optoelectronic devices

A low temperature solution-processed MoO3 (sMoO3) thin film with a facile method for organic optoelectronic devices is developed. The film is extremely smooth with a root mean square (RMS) roughness of 0.318 nm, which is a significant advance for fabricating devices. An X-ray photoelectron spectroscopy (XPS) measurement shows that the sMoO3 possesses few Mo5+ states with a Mo : O stoichiometry of 2.99, demonstrating a nearly ideal MoO3 stoichiometry at a low annealing temperature. The sMoO3 film exhibits a superior hole injection ability in both an organic light-emitting diode (OLED) and organic photovoltaic cell (OPV), compared to conventional hole injection material poly (3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). It is proved that the sMoO3 fabricated by the simple and low-cost method is an excellent alternative to a PEDOT:PSS anode buffer layer for solution-processed organic optoelectronic devices.

Efficient light trapping in inverted polymer solar cells by a randomly nanostructured electrode using monodispersed polymer nanoparticles

The randomly nanotextured back electrode provides a simple and efficient route for enhancing photocurrent in polymer solar cells (PSCs) by light trapping, which can increase light absorption within a finite thickness of the active layer. In this study, we incorporated mono-disperse 60 nm polystyrene nanoparticles (PS NPs) into a 50 nm thick poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) anode buffer layer (ABL) to create a randomly nanotextured back electrode with 10 nm height variations in inverted-type PSCs. The roughened interface between the PS NP-PEDOT:PSS ABL and the Ag electrode scatters light in the visible range, leading to efficient light trapping within the device and enhanced light absorption in the active layer. Inverted PSCs with randomly nanotextured electrodes (φ(NP) = 0.31) showed short-circuit current density (J(SC)) and power conversion efficiency (PCE) values that were 15% higher than those of control devices with flat electrodes. External quantum efficiency, reflectance, and optical light scattering as a function of ϕ(NP) were examined to determine the origin of the enhancement in J(SC) and PCE.

Nanosphere Templated Continuous PEDOT:PSS Films with Low Percolation Threshold for Application in Efficient Polymer Solar Cells

Nanometer-sized monodisperse polystyrene nanospheres (PS NS) were designed as an opal template for the formation of three-dimensionally continuous poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films. The resultant films were successfully applied as the anode buffer layer (ABL) to produce highly efficient polymer solar cells (PSCs) with enhanced stability. The conductivity of the PS NS-PEDOT:PSS films was maintained up to ø(PS) = 0.75-0.80, indicating that the formation of continuous PEDOT:PSS films using PS NS templates was successful. To demonstrate the applicability of the PS NS-PEDOT:PSS film for organic electronics, the PS NS-PEDOT:PSS films were used as ABLs in two different PSCs: P3HT:PCBM and P3HT:OXCBA. The photovoltaic performances of both PSCs were maintained up to ø(PS) = 0.8. In particular, the power conversion efficiency of the P3HT:OXCBA PSC with a PS NS-PEDOT:PSS ABL (ø(PS) = 0.8) was greater than 5% and the air stability of the device was significantly enhanced.