Titanium dioxide (TiO₂) based planar perovskite solar cells (PSCs) suffer from poor long-term stability and show hysteretic behaviour in the device characteristic curve. In addition to the exceptional bulk properties of the perovskite, the performance and stability are also highly dependent on the conduction band energy, conductivity, and electronic trap states of the TiO₂ compact layer (CL). In this work, single-phase brookite (BK) TiO₂ nanoparticles (NPs), synthesized via a hydrothermal method using a water-soluble titanium complex, are incorporated as a bridge between the perovskite and TiO₂ CL. This resulted in uniform large perovskite grain growth with enhanced crystallinity, significant reduction in trap/defect sites and interfacial recombination as revealed by scanning electron microscopy (SEM), photoluminescence (PL), and impedance spectroscopy results, respectively. The resulting PSCs show highly reproducible power conversion efficiencies (PCEs) up to ∼18.2% (vs. ∼15%) with a stable performance of 18% under continuous light illumination (1 sun) at the maximum power point tracking (MPPT) in contrast to only TiO₂ CL based planar devices. To the best of our knowledge, this is so far the best photo-stability data reported for brookite NP based PSCs. Based on our present study, at the end we provide further direction to enhance the stability of planar PSCs.

中文翻译：

---

单相板钛矿TiO2纳米粒子桥增强钙钛矿太阳能电池的稳定性

基于二氧化钛（TiO ₂）的平面钙钛矿太阳能电池（PSC）长期稳定性较差，并且在器件特性曲线中显示出滞后行为。除了钙钛矿具有出色的整体性能外，其性能和稳定性还高度取决于TiO ₂致密层（CL）的导带能，电导率和电子陷阱态。在这项工作中，通过水热法使用水溶性钛配合物合成的单相板钛矿（BK）TiO ₂纳米颗粒（NPs）作为钙钛矿和TiO ₂之间的桥梁被纳入CL。分别通过扫描电子显微镜（SEM），光致发光（PL）和阻抗谱分析显示，这导致钙钛矿晶粒均一且具有较大的晶体生长，并具有增强的结晶度，陷阱/缺陷部位和界面重组的明显减少。将所得的PSC显示高度可重现的功率转换效率（PCE的）至多~18.2％（相对于〜15％）与18％下，在与此相反的最大功率点跟踪（MPPT）连续光照明（1太阳）稳定的性能仅限于TiO ₂ CL基平面器件。据我们所知，这是迄今为止报道的基于板钛矿NP的PSC最好的光稳定性数据。根据我们目前的研究，最后，我们提供了进一步的方向来增强平面PSC的稳定性。