Polyimide transparent electrode graphene integrated booster flexible organic solar cell! Efficiency of over 15%!

With the continuous development of flexible electronics industry, flexible organic solar cells due to the lightweight, low-cost, easy processing advantages and flexible wearable huge potential of energy during the show received widespread attention. However, the flexible organic solar cell efficiency compared with the battery prepared with rigid rigid substrates still a large gap, one of the main electrode is prepared based on flexible transparent plastic substrate in sheet resistance, transparency, processability, and stability aspect was extremely restricted. Thus, development of excellent optical and electrical properties, low surface roughness and high mechanical and thermal stability of the transparent electrode, is particularly critical in promoting the development of flexible organic solar cell. Recently, Ulsan National Institute of Science and Technology (UNIST) Professor Changduk Yang and Professor Hyesung Park team A polyimide prepared – graphene (PI @ GR) new transparent electrode applied to a flexible organic solar cell, achieved 15.2 % of the photoelectric conversion efficiency is reported so far maximum value of the flexible organic solar cell. Wherein, as the PI carrier film and the graphene graphene electrode substrate, the electrode provides a relatively high thermal stability. Multi-graphene layers of the assembly into close contact improves the adhesion between the electrode and the substrate, increases the mechanical stability of the electrode. Meanwhile, the graphite electrode surface alkenyl This preparation method for presenting ultraclean ultra-smooth surface features, a light transmission of 92%, the resistance as low as 83 Ω / sq, ultra-smooth surface of the electrode also help to reduce the battery interface defects, and thus high booster constructed flexible organic solar cell. 聚酰亚胺集成石墨烯透明电极助力柔性有机太阳能电池!效率超15%! The work entitled \”Flexible Organic Solar Cells Over 15% Efficiency with Polyimide-Integrated Graphene Electrodes\” published in \”Joule\”. Ulsan National Institute of Science and Technology, Professor Changduk Yang and Professor Hyesung Park co-corresponding author for the paper.

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FIG high conductivity flexible transparent PI @ GR Process for preparing an electrode

A polyamic acid (PAA) imidization method synthesisColorless polyimides (CPI) (FIG. 1A) because of its good thermal stability, good flexibility and high light transmittance, in the photovoltaic device having a great potential as a flexible substrate. Therefore in the present work as a PI flexible substrate graphene flexible transparent electrodes (PI @ GR) was prepared, the preparation process shown in FIG. 1B: On the first growing a high quality graphene on the Cu substrate by the CVD method, and then directly in the graphite alkenyl PAA spin coated on a colorless transparent cured after PI, after etching away the polyimide Cu monolayer obtained – graphene thin film. After repeated layer by layer assembly thus obtain a high conductivity PI @ GR flexible transparent electrodes applied to the flexible organic solar cell.

The optical, electrical properties and surface morphology of the flexible transparent electrode of FIG. 2 PI @ GR Characterization

This work layer by layer superimposed on the film by a single graphene PAA coating, a multilayered graphene electrode, maintain the integrity of graphene overlay process, thus contributing to improved electrode performance. Successfully prepared PI @ GR respective Raman spectra confirmed. And the optical and electrical properties of the test results show, PI @ GR transparent electrode having good light transmittance and low sheet resistance. Further, compared to a conventional plastic substrate graphene electrode (PET / GR and PI / GR) features a typical residual PMMA (PMMA insulating performance may deteriorate electrical properties of the graphene electrode), PI @ GR ultra clean and super smooth surface features, help enhance the electrode performance and reduce interfacial contact resistance, thereby improving the device performance of the solar cell.

FIG. 3 PI @ GR flexible transparent electrode of mechanical and thermal stability

PI @ GR good mechanical stability and a flexible transparent electrodes but also for its thermal stability Construction High performance flexible organic solar cell to provide effective protection. The method of direct integration in the PI layer graphene strengthened the bonding interface, so that the PI @ GR compared to conventional plastic graphene electrode group having a more excellent mechanical stability. Performing a radius of 5 mm, the number of cycles of the bending test of 10,000 times, resistance remains almost constant (FIG. 3). Further, based on high temperature properties of PI, PI @ GR electrode has a high thermal stability, improved the effect of the traditional preparation of flexible organic solar cell during the high temperature annealing processSo that the battery performance suffers problems.

FIG 4 based on the performance PI @ GR transparent electrode flexible organic solar cell

Finally, based on PI @ GR flexible transparent electrode having excellent optical and electrical properties, as well as its outstanding mechanical and thermal stability, which is applied to build efficient flexible organic solar cell. As shown, PI @ GR-yl 4 projecting flexible organic solar cell performance, the photoelectric conversion efficiency of up to 15.2%, is reported in the most flexible organic solar cell efficiency, even comparable to glass / ITO substrate cell rigid (15.7% ).


In this study, the authors successfully developed with excellent optical and electrical properties, good mechanical and thermal stability of the PI @ GR flexible transparent electrode, and applied to a flexible organic solar battery to achieve a record high 15.2% photoelectric conversion efficiency, will help promote the development of flexible organic solar cells. Meanwhile, the transparent electrodes graphene proposed in this work offers great potential for building the next generation of high performance flexible photovoltaic device. Original link: https: //www.sciencedirect.com/science/article/abs/pii/S2542435120300908