高效无空穴传输层碳基钙钛矿太阳能电池的制备与性能研究

碳基钙钛矿太阳能电池因稳定性高、成本低廉而备受关注，但由于钙钛矿与碳电极之间能级匹配度不高，界面阻力大而导致效率不及金属基钙钛矿太阳能电池.本文制备了碳基无空穴传输层FTO/c-TiO₂/m-TiO₂/CH₃NH₃PbI₃/Carbon电池结构.通过对介孔二氧化钛层、钙钛矿层厚度进行优化，并对钙钛矿的薄膜形貌及钙钛矿激发电子寿命、可见光吸收度、载流子的提取与分离等进行深度分析，讨论了电池效率提升的内在机理.当介孔氧化钛层和钙钛矿层达到最优厚度时，钙钛矿太阳能电池获得了开路电压（V_oc）为0.93 V、电流密度（J_sc）为21.75 mA/cm²、填充因子为55%、光电转化效率达到11.11%.同时对电池进行了稳定性研究，在室温湿度为40%–50%的条件下放置15 d电池性能依旧稳定保持原来的95%，优于金属基钙钛矿太阳能电池，从而为碳电极钙钛矿太阳能电池的商业化发展提供了可能.

Preparation and performance of high-efficient hole-transport-material-free carbon based perovskite solar cells

Carbon based perovskite solar cells (C-PSCs) have attracted much attention because of their high stability and low-cost of production. However, due to the high interfacial resistance and the low energy level matching between perovskite and carbon electrodes, the maximum power conversion efficiency (PCE) is less than that of the metal-based perovskite solar cells. In this paper, a carbon-based perovskite solar cell is fabricated with the device structure of FTO/c-TiO₂/m-TiO₂/CH₃NH₃PbI₃/Carbon. The perovskite films and carbon based perovskite solar cells are characterized by scanning electron microscope, atomic force microscope, X-ray diffraction (XRD), UV-Vis absorption spectrum, the steady-state spectrum, the time-resolved PL (TRPL) spectrum, and an electrochemical workstation. In addition, the internal mechanism of the efficiency improvement of carbon-based perovskite solar cell is discussed in depth. Then, the rotation speeds of mesoporous TiO₂ layer (TiO₂ paste diluted by ethanol with mass ratio of 1:4) are 1500, 1600, 1700 and 1800 r/min and the speeds of perovskite layer (CH₃NH₃I and PbI₂ at a 1:1 molar ratio are stirred in a mixture of DMF and DMSO (9:1, v/v)) are 2000, 3000, 4000 and 5000 r/min; When the speed of m-TiO₂ layer is 1700 r/min and the speed of perovskite layer is 4000 r/min, the mesoporous TiO₂ layer thickness is about 500 nm, Thickness of CH₃NH₃PbI₃ capping layer is about 400 nm. The cooperation of these two layers eventually leads to the high-quality perovskite with enlarged grain size, prolonged photoluminescence lifetime, lowered defect density, increased carrier concentration, and the finally enhanced photovoltaic performance. The device obtains the highest PCE of 11.11% with an open circuit voltage (V_oc) of 0.93 V, a current density (J_sc) of 21.75 mA/cm² and fill factor (FF) of 55%. At the same time, the stability of the carbon-based perovskite solar cell is also studied. The XRD is used for initial perovskite and the perovskite after 15 days to investigate the photo- and humidity stability of the full cells without encapsulation. The device exhibits excellent air stability with only 5% degradation when aged in ambient air at room temperature with 40%-50% humidity without any encapsulation after 15 days, which is better than the metal based perovskite solar cell. Our results open the way for making cost-efficient and stable PSCs toward market deployment.