研究背景
基于超柔性织物的顶部发光有机发光器件 (Fa-TOLED) 具有孔径比大、效率高和机械灵活性强等优点，被认为是可穿戴有源矩阵显示器的理想候选器件。尽管最近在顶发光器件的器件效率和机械柔性方面取得了突破性进展，但在实现更经济、更高效的可扩展大规模制造 Fa-TOLED 的战略方面仍存在挑战。一旦克服了这些挑战，Fa-TOLED 在智能柔性/可穿戴显示器中的应用就会大大受益。构建 TOLED 最广泛采用的策略是真空沉积从底部反射电极到顶部半透明金属电极的所有功能层。在这种情况下，不仅成本高昂，而且由于这些顶部发光器件中反射电极和半透明金属电极之间的光反射不可避免地会产生微腔效应，从而导致与角度相关的发射光谱和非朗伯发射特性。然而，在不影响器件性能的前提下，通过制造和集成溶液加工的柔性反射底电极 (FRBE)和柔性透明顶电极(FTTE)来实现高效的全溶液加工 TPLED 还不够完美。FRBE 对于顶发光器件至关重要，因为它们可以通过反射效应诱导近双倍发光，从而显著提高器件效率。然而，印刷过程需要专门配制的可印刷油墨、精心调整的油墨流变性和润湿性以及相对较厚的沉积膜。银纳米线(AgNWs)和导电聚合物等前瞻性 FTTE 材料具有优异的光电特性、机械柔性和溶液加工性，已在高性能柔性光电器件中得到应用。坦率地说，本征 AgNWs 电极的粗糙表面会导致较大的漏电流甚至短路。此外，当 FTTES 油墨或溶液直接涂覆在有机层上时，溶剂会溶解或渗透底层薄膜，从而导致器件性能下降。软接触层压技术为建立良好的电接触开辟了一条大有可为的途径，可避免在溶液处理过程中出现底层破坏和溶剂渗透。为了实现良好的电接触，层压工艺通常需要加入粘合剂层、加热/等离子处理和加压以增强界面亲和力,这会降低器件性能，甚至由于潜在的机械损伤而损害基于柔性织物的器件。
研究成果
基于织物的低成本顶部发光聚合物发光器件 (Fa-TPLED) 因其在可穿戴显示器中的显著潜在应用而受到越来越多的关注。然而，要实现大规模制造从底部电极到顶部电极的高效全溶液加工器件仍具有挑战性。南京邮电大学陈月花&张新稳教授等人介绍了通过一步银镜反应在织物上集成的光滑反射银阳极以及通过水辅助剥离法在织物上集成的PDMS/Ag NWs/PEDOT:PSS复合透明阳极，这两种器件都具有优异的光电特性和强大的机械柔韧性Fa-TPLED 是通过在底部反射阴极上旋涂功能层和在顶部透明阳极上层压而制成的。FaTP-LED 的电流效率为 16.3 cdA-1外部量子效率为 4.9%，电致发光光谱与角度无关。此外Fa-TPLED 还具有出色的机械稳定性，在半径为 4 毫米的条件下弯曲 200 次后，其电流效率仍保持在 14.3 cd A-1。研究结果表明，溶液加工的反射阴极和透明阳极的整合为构建低成本、高效率的织物基器件提供了一条新途径，在新兴的智能柔性/可穿戴电子产品中显示出巨大的应用潜力。相关研究以“Efficient Flexible Fabric-Based Top-Emitting Polymer Light-Emitting Devices for Wearable Electronics”为题发表在Small期刊上。
图文导读
Figure 1. Schematic illustration of the fabrication procedure of Fa-Ag electrodes.
Figure 2. a) Photograph of the fabricated Ag electrode on the glass substrate by silver mirror reaction. b) Photograph of the patterned Fa-Ag electrode. c) Thickness of the Ag film with increasing reaction time under 55 °C. Microscopic morphologies of the Fa-Ag electrode: d) cross-section SEM image, e) enlarged cross-section SEM image, f) top-view SEM image, and g) AFM image. h) Spectra of mirror reflection and diffuse reflection. Inset: the reflection photograph of the Fa-Ag electrode. i) Variations of sheet resistance with the bending cycles at a bending radius of 4 mm. Inset: the schematic diagram of Fa-Ag electrodes under outward and inward bending.
Figure 3. a) Schematic diagram of the water-assisted peeling process for the PDMS/AgNWs/PEDOT:PSS electrode, photographs of the glass/PEDOT:PSS/AgNWs electrode and the transferred PDMS/AgNWs/PEDOT:PSS electrode. SEM images: b) glass/PEDOT:PSS/AgNWs electrode and c) PDMS/AgNWs/PEDOT:PSS electrode. Water contact angles: d) glass substrate, e) glass substrate after peeling off PDMS in DI water, f) glass substrate after peeling off PDMS/AgNWs/PEDOT:PSS in DI water, g) PDMS/AgNWs/PEDOT:PSS electrode. h) XPS spectra of the pristine PEDOT:PSS,the peeled PDMS/PEDOT:PSS and the glass substrate after peeling off PDMS/PEDOT:PSS in DI water. Peeling mechanisms: i) in air, j) in DI water.
Figure 4. a) Sheet resistance of the PEDOT:PSS and AgNWs/PEDOT:PSS electrodes (before and after peeling off). b) Transmittance of the PDMS/PEDOT:PSS and PDMS/AgNWs/PEDOT:PSS electrodes. Inset: the photograph of the PDMS/AgNWs/PEDOT:PSS electrode. Variations of sheet resistance for the PDMS/AgNWs/PEDOT:PSS electrode with c) bending radius (1–8 mm) and d) bending cycles (bending radius of 4 mm). Inset: the schematic diagram of outward and inward bending. Photographs of a yellow LED with PDMS/AgNWs/PEDOT:PSS electrodes as electrical wires under the bending test: e) before bending and f) after 1000 bending cycles with a bending radius of 4 mm.
Figure 5. a) Schematic diagram of the lamination process of Fa-TPLEDs. b) Device structure of the laminated Fa-TPLEDs. Characteristics of the bottom[1]emitting PLEDs and the laminated Fa-TPLEDs before bending and after 200 bending cycles (bending radius r = 4 mm): c) current density–voltage,d) luminance–voltage, inset: the photograph of the pristine Fa-TPLEDs and bending Fa-TPLEDs with a bending radius of 4 mm, e) current efficiency–luminance, and f) EQE–luminance. g) Variable angle EL spectra of the Fa-TPLEDs. Inset: the angular dependence of EL intensities. h) Repeated bending test of the Fa-TPLEDs with 200 cycles at a bending radius of 4 mm. i) Repeated bending test of the Fa-TPLEDs with 200 cycles at different bending radius. j) Photograph of the Fa-TPLED working under the bending state (a bending radius of 4 mm). k) Photographs of various patterned large-area Fa-TPLEDs.
总结与展望
作者展示了一种简便的全溶液工艺，用于制造 Fa-Ag 反射阴极和PDMS/AgNWs/PEDOT:PSS 透明阳极，以实现低成本、高效率的 Fa-TPLED 。通过一步银镜反应在织物上集成的光滑反射Fa-Ag阴极具有94%的高反射率和优异的机械稳定性。通过采用水辅助剥离策略隶属于 PDMS/AgNWs/PEDOT:PSS 的透明阳极具有84%的透光率、~80 Ω sq-1 的薄层电阻和良好的机械柔韧性。同时，作者系统地研究了在去离子水中 PDMS/AgNWs/PEDOT:PSS 与玻璃界面之间的分离和调节机制。通过水的渗透，相分离发生，同时 H 键效应减弱，润湿性增强。通过软接触层压构建的 Fa-TPLED 显示出 16.3 cd A-1的电流效率、4.9% 的外部量子效率和与角度无关的 EL 光谱。特别是Fa-TPLED 显示出很高的可变形性，在半径为 4 mm的条件下弯曲 200 次后，仍能保持 87% 的初始亮度。各种大面积 FaTPLED 标识的实现，阐明了我们的低成本、简便策略在全溶液加工智能柔性/可穿戴电子产品中的巨大潜力。
文献链接
Efficient Flexible Fabric-Based Top-Emitting Polymer Light-Emitting Devices for Wearable Electronics
https://doi.org/10.1002/smll.202305327
转自：“i学术i科研”微信公众号
如有侵权，请联系本站删除！
