有机-无机杂化钙钛矿太阳能电池因其优异的光电特性、 低廉的制备成本、 高效的转换效率等优越特性, 成为光伏领域的研究热点。 电子传输层作为钙钛矿电池的核心层, 主要起到提取和传输光生载流子的作用, 且能够作为空穴阻挡层, 抑制钙钛矿活性层中电荷复合, 所以优异性能的电子传输层对钙钛矿太阳能电池的发展至关重要。 可目前钙钛矿光伏器件常用的刚性电子传输层(介孔层或致密层)均需要高温烧结, 这限制了其在柔性钙钛矿器件方面的应用。 因此, 开发一种可应用于钙钛矿光伏领域的柔性电子传输层成为当前亟待解决的问题之一。 纳米ZnO具有合适的能级和较高的电子迁移率, 且可以通过低温制备, 被广泛应用在光伏器件中作为电子传输层。 因此, 通过旋涂法和静电纺丝法分别制备了刚性纳米ZnO和柔性纳米ZnO电子传输层, 确定了静电纺丝法制备柔性纳米ZnO的最佳制备工艺。 利用扫描电子显微镜、 X射线衍射仪、 紫外可见分光光度计和稳态/瞬态荧光光谱系统研究了刚性和柔性纳米ZnO对钙钛矿薄膜形貌、 结构和光谱性能的影响。 结果表明, 钙钛矿薄膜的形貌对基底纳米ZnO的形貌依赖性很强。 而基于刚性和柔性纳米ZnO的钙钛矿薄膜几乎呈现相同的结构和光谱吸收范围, 荧光发射峰均在770 nm附近, 且柔性纳米ZnO的荧光猝灭效率为82%, 几乎和刚性纳米ZnO的荧光猝灭效率(85%)相媲美。 进一步, 根据瞬态荧光动力学数据计算获得刚性和柔性纳米ZnO的界面电荷分离效率分别为61%和41%, 这表明通过静电纺丝法制备的柔性纳米ZnO具备一定的界面电荷分离能力, 有望成为新型的柔性电子传输层。 这对柔性基底钙钛矿太阳能电池的设计具有重要参考价值, 对促进钙钛矿光伏应用具有现实意义。

Organic-inorganic hybrid halide perovskite solar cells have become a research hotspot in the photovoltaic field due to their excellent photoelectric properties, low preparation costs, and high conversion efficiency. As the core layer of perovskite devices, the electron transport layer mainly plays a role in extracting and transporting photogenerated charge carriers, and can serve as a hole blocking layer to suppress charge recombination in the perovskite active layer. Therefore, excellent performance of the electron transport layer is crucial for developing perovskite solar cells. However, the rigid electron transport layer (mesoporous or compact layer) commonly used in perovskite photovoltaic devices currently requires high-temperature sintering, which limits its application in flexible perovskite devices. Therefore, developing a flexible electron transport layer that can be applied in the field of perovskite photovoltaics has become an urgent problem to solve. Nano ZnO has suitable energy levels and high electron mobility and can be prepared at low temperatures, widely used as an electron transport layer in photovoltaic devices. Therefore, this work prepared rigid and flexible nano ZnO electron transport layers using spin coating and electrospinning methods, respectively, and determined the optimal preparation process for flexible nano ZnO using the electrospinning method. The effects of rigid and flexible nano ZnO on perovskite thin films' morphology, structure, and spectral properties were systematically studied by scanning electron microscopy, X-ray diffraction, UV-Vis absorption spectroscopy, and steady-state/transient fluorescence spectroscopy. The results indicate that the morphology of perovskite films strongly depends on the morphology of substrate nano ZnO. The perovskite thin films based on rigid and flexible nano ZnO exhibit almost the same structure and spectral absorption range (400~800 nm), with fluorescence emission peaks around 770 nm. The fluorescence quenching efficiency of flexible nano ZnO is 82%, almost comparable to that of rigid nano ZnO (85%). Furthermore, based on transient fluorescence kinetics data, the interfacial charge separation efficiencies of rigid and flexible nano ZnO were calculated to be 61% and 41%, respectively. It indicates that the flexible nano ZnO prepared by electrospinning has certain interfacial charge separation capabilities and is expected to become a new type of flexible electron transport layer. It provides an important reference value for designing flexible substrate perovskite solar cells and has practical significance for promoting perovskite photovoltaic applications.