钙钛矿的纳米压印图案化及其光伏性能研究

Perovskite solar cells have many advantages, such as low weight, low fabrication cost, low-temperature solution-based processing and designability. However, for thermodynamic reasons, the resulting polycrystalline perovskite films are often inhomogeneous, which leads to shunting in the solar cells based on these layers and lower performance. For the perovskite thin film, the formation of pin holes and incomplete coverage of the substrate resulting low-resistance shunting paths. Besides, it is difficult to produce large-area, uniformly high-quality perovskite films and the power conversion efficiency will substantially reduce when a small device is scaled up. To circumvent these obstacles, in this project, nanoimprint lithography (NIL) is proposed to directly pattern into perovskites to produce high-quality perovskite films. During imprint, the polycrystalline perovskite appears to recrystallize, and the crystallinity, coverage and grain size the resulting layers are significantly improved. Moreover, the shape, size and quantity of the nanostructure for the patterned perovskite film can be tailored at molecular scale. The universality of the NIL will be improved by comparing various perovskite materials. In this case, large-area, uniformly high-quality perovskite films could be prepared and high efficient perovskite solar cells could be fabricated.

钙钛矿太阳能电池具有质轻、价廉、可溶液加工和可设计等一系列优点，近几年得到广泛研究。然而，由于热力学不稳定性，钙钛矿层在加热成膜的过程中往往会出现聚集的现象，从而导致钙钛矿太阳能电池出现短路现象，降低器件的性能。针对钙钛矿薄膜易出现孔洞和覆盖不完全从而导致钙钛矿太阳能电池出现短路现象，以及大面积制备高质量钙钛矿薄膜困难而导致大面积钙钛矿太阳能电池效率低等问题。本项目拟采用纳米压印技术来对钙钛矿层来进行压印处理，从而来提高钙钛矿薄膜的结晶性、覆盖率和晶粒尺寸等，实现在纳米尺度上对钙钛矿薄膜图案的形状、尺寸以及数量等进行有效、精确地调控。通过多方面、多层次的研究，来最大化纳米压印技术在钙钛矿薄膜制备处理中的优点，提高纳米压印在钙钛矿薄膜中的普适性，实现大面积高质量钙钛矿薄膜的制备，得到高性能和高稳定性的钙钛矿太阳能电池。

本项目通过纳米压印技术、添加剂改性和前驱体溶液胶粒行为调控以及界面层改性来提高钙钛矿薄膜的质量，降低薄膜缺陷，改善薄膜形貌，提高薄膜结晶性，从而获得高效稳定的钙钛矿太阳电池，利用刮涂技术实现大面积钙钛矿太阳电池的制备。通过发展一种有效的平面纳米压印（PiP）方法来促进钙钛矿薄膜的再结晶，优化其结晶，显著改善薄膜形貌和提高薄膜质量。通过对形貌和力学模拟结果的分析，揭示了优质钙钛矿晶粒的形成过程。最终PiP处理的太阳电池的最高PCE达到了20.52%。此外，经过PiP处理的薄膜在25°C和≈60%湿度的空气中存放35天后，效率几乎没有明显的降解。创新性提出利用表面能驱动诱导自发形成梯度分布的二维结构，将疏水性间隔阳离子铵盐4-(三氟甲基)苄胺(4TFBZA)引入构建表面梯度二维(SUG-2D)结构，有效地钝化了陷阱态，抑制了离子扩散。SUG-2D钙钛矿薄膜及其器件表现出良好的热稳定性和湿度稳定性。最终，SUG-2D结构钙钛矿器件的PCE达到了17.07%。针对大面积印刷过程中极易出现的微米级缺陷，提出了多尺度的缺陷策略来实现大面积柔性钙钛矿的加工制备。将醋酸甲胺作为墨水辅助剂引入到前驱体溶液中，可以有效调控钙钛矿胶体粒子的聚集行为。此外，通过预先沉积4-氯苯磺酸于电极表面，来实现更稳定的钙钛矿界面，最终基于1.01 cm2的刮涂器件得到了18.12%的光电转换效率和提高的空气气氛稳定性。相关成果已在国际权威刊物如Adv. Mater. (1篇IF: 30.849); Adv. Funct. Mater. (2篇IF: 18.808); J. Mater. Chem. A (1篇IF: 12.732) 和Sci. China Chem (1篇IF: 9.445) 等上相继发表论文12篇。授权发明专利2项，作为第六完成人获教育部自然科学奖二等奖1项，第二完成人获省级教学成果奖二等奖。