界面植入卤化碳点构建高效稳定的柔性钙钛矿太阳能电池

The interfacial embedding of halogen-terminated carbon dots produces highly efficient and stable flexible perovskite solar cells

有机无机杂化钙钛矿薄膜的可低温溶液法制备为其在柔性太阳能电池上的应用提供了发展契机,然而,由于钙钛矿的离子性和脆性,柔性钙钛矿器件在环境稳定性和力学稳定性方面仍面临巨大挑战。本文基于激光衍生的卤化碳点在钙钛矿多颗粒界面的植入,提出了一种提高钙钛矿薄膜柔性和环境稳定性的化学交联普适策略。一系列的卤化碳点可通过脉冲激光辐照卤代苯溶剂原位生成,并通过反溶剂方法植入至钙钛矿薄膜表面和晶界。结果表明,钙钛矿与碳点之间强的相互作用有利于钙钛矿薄膜的缺陷钝化、晶格锚定以及载流子动力学调控。基于界面植入的柔性钙钛矿太阳能电池最高光电转换效率达到20.26%,且未封装的器件在40%相对湿度下经90天仍能保持其初始效率的90%以上,在85°C下的热稳定性能稳定超过200 h。此外,界面植入的柔性器件也展现了优异的抗变形能力,例如,经500次弯曲循环(曲率半径为4 mm)后仍能保留超过80%的初始效率。

Organic-inorganic hybrid perovskite films made by low-temperature solution processing offer promising opportunities to fabricate flexible solar cells while formidable challenges regarding their environmental and mechanical stability remain due to their ionic and fragile nature.This work explores the possibility of chemical crosslinking between adjacent grains by the interfacial embedding of laser-derived carbon dots with halogen-terminated surfaces to improve the flexibility and stability of the polycrystal-line films.A series of halogen-terminated carbon dots was generated in halobenzene solvents by pulsed laser irradiation in the liquid,and were then placed in the surface and grain boundaries of the perovskite film by an antisolvent procedure,where an immiscible solvent was poured onto the coating surface with a suspension containing carbon dots and perovskite precursors to cause precipita-tion.Strong interaction between perovskite and the carbon dots results in effective defect passivation,lattice anchoring and a change in the carrier dynamics of the perovskite films.Because of this,unencapsulated flexible perovskite solar cells after the interfacial em-bedding have power conversion efficiencies up to 20.26%,maintain over 90%of this initial value for 90 days under a relative humid-ity of 40%and have a thermal stability of 200 h even at 85°C.The flexible devices withstand mechanical deformation,retaining over 80%of their initial values after 500 bend cycles to a radius of curvature of 4 mm.