基于功函可调的氧化石墨烯衍生物高效率柔性钙钛矿太阳能电池的界面工程

The interface layer is a crucial factor in high efficiency perovskite solar cells. Metal oxides are often employed as electron transport materials to date. However, the low electron mobility and high temperature fabrication process is detrimental to high efficiency solar cells. In order to solve the two problems, we will exploit the graphene oxide (GO) derivatives with high carrier mobility and preparation of low temperature as the interface materials. On the one hand, the work function of GO will reduced by doping lithium elements, and adversely increased by doping chlorine elements. The peorvskite solar cells will be fabricated with Li-GO and Cl-GO as electron transport layers and hole transport layers, respectively. The electron and hole transport rate trends to balance due to the almost equal electron and hole mobility of the two different GO derivatives, facilitating to eliminate current-voltage hysteresis in perovskite solar cells. Meanwhile, the work function of GO derivatives will be tuned by controlling the doped ratio of Li and Cl elements, leading to well match with energy level of perovskite materials, and contributing to the high efficiency of the perovskite solar cells. Based on the deep research of these results, we will understand the key role of interface materials in the perovskite solar cells, and effectively deduce the principle of choice for the interface materials. On the other hand, the interface layers based on GO derivatives can be prepared on flexible substrates using a solution processed method at low temperature, providing a practical route for the low cost and high efficiency flexible perovskite solar cells.

界面层在高效率钙钛矿太阳能电池中至关重要。针对目前使用最多的金属氧化物电子传输层较低的电子迁移率以及需高温处理的问题，本项目拟采用具有高载流子迁移率、可低温溶液加工的氧化石墨烯衍生物作为界面层，分别对其进行锂和氯元素掺杂得到低功函锂掺杂还原氧化石墨烯以及高功函氯掺杂氧化石墨烯作为电子和空穴传输层，使电子和空穴的传输趋于平衡，消除钙钛矿电池的电流-电压滞后效应。通过调控锂和氯元素的掺杂比例，实现氧化石墨烯衍生物功函的连续可调，使其可以很好的与钙钛矿材料能级进行匹配，提高钙钛矿电池的效率。通过研究电池中载流子在界面处的传输机制，揭示界面层在消除电流-电压滞后效应以及提高光电性能中所起的关键作用，为钙钛矿电池中界面材料的选择提供有力的理论指导。同时利用氧化石墨烯可低温溶液加工的优势，克服目前高温制备界面层的高功耗和不能在柔性基底上沉积的难题，为柔性高效率钙钛矿太阳能电池的制备提供可行的技术路线。

柔性太阳能电池由于具有质量轻，运输方便，可折叠等突出优点，可将其应用于许多特殊领域，例如可穿戴电子器件、手提式充电机、远程供能、空间站等。柔性钙钛矿太阳能电池中，高质量的低温界面层和钙钛矿吸光层对其性能的提升至关重要。本项目中，我们采用氧化石墨烯对传统的空穴传输层进行掺杂，极大的提升了其空穴迁移率，可有效收集钙钛矿中产生的载流子；开发了新型低温界面材料，通过调控功函、降低传输电阻等，进一步提升钙钛矿太阳能电池的效率。同时，我们开发了多种有效的钙钛矿制备方法和钙钛矿前驱体溶液的添加剂，有效减少了钙钛矿吸光层中的缺陷态密度，增大了钙钛矿结晶颗粒的尺寸以及提升了器件中载流子的寿命，结合以上界面层材料，制备了高效率且无电流-电压滞后效应的钙钛矿太阳能电池，并对其结果进行了Newport的认证。通过对钙钛矿太阳能电池中载流子传输动力学的研究，证明器件中载流子的传输平衡可有效消除电流-电压滞后效应。通过本项目的研究，将对钙钛矿太阳能电池中载流子的传输机制产生更深刻的认识，开发的革新性的低温界面层材料将为柔性钙钛矿太阳能电池的制备提供可行的技术路线。