Hybrid organic inorganic perovskites (HOIPs) have emerged as the most promising next-generation photovoltaic (PV) materials. However, syntheses of HOIPs not only require a controlled environment but also their long term stability is a major challenge. Herein, we report mechanochemical synthesis of highly stable CH₃NH₃PbBr₃ (MAPbBr₃) powder under an open atmosphere that undergoes no phase change even after 6 months. The MAPbBr₃ exhibits a large dielectric constant of >10⁴ in the frequency regime of 1 Hz to 10⁶ Hz and in a wide temperature range of 300–475 K because of its inherent charge carrier, which is contended for the low exciton binding energy in HOIPs, leading to superior PV performance as compared to the solution-based synthesized MAPbBr₃. The excitonic activation energy measured from the ac conductivity study in the same temperature range is 5 meV, which suggests facile exciton separation and generation of free charge carrier upon irradiation. The PV performance of the as-synthesized MAPbBr₃ is investigated by fabricating two thin-film based device architectures without the hole-transporter layer, that is, FTO/MAPbBr₃/Ag and FTO/TiO₂/MAPbBr₃/Ag, exhibiting a photo conversion efficiency of 4.2 and 7.31%, respectively. In contrast to the thermally evaporated metal counter electrode (e.g., Au and Ag), the spin-coated Ag film from solution is used as top contact here, thereby improving the cost-effectiveness and metal-electrode fabrication impediments.

中文翻译：

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机械化学合成的稳定CH ₃ NH ₃ PbBr ₃在无空穴传输器的太阳能电池中的超大介电常数和优异的光伏性能

杂化有机无机钙钛矿（HOIP）已成为最有前途的下一代光伏（PV）材料。然而，HOIP的合成不仅需要受控的环境，而且它们的长期稳定性也是主要的挑战。在此，我们报道了在开放的气氛下，即使经过6个月也没有相变的情况下，机械化学合成高度稳定的CH ₃ NH ₃ PbBr ₃（MAPbBr ₃）粉末。MAPbBr ₃在1 Hz至10 ⁶的频率范围内表现出大于10 ⁴的大介电常数它具有固有的电荷载流子，可在300 Hz至475 K的宽温度范围内进行竞争，这是因为HOIP中的激子结合能低，因此与基于溶液的合成MAPbBr ₃相比，PV性能更高。根据在相同温度范围内的交流电导率研究测得的激子活化能为5 meV，这表明容易进行激子分离并在辐照时生成自由电荷载流子。通过制造两种没有空穴传输层的基于薄膜的器件架构，即FTO / MAPbBr ₃ / Ag和FTO / TiO ₂ / MAPbBr _3，研究了合成后的MAPbBr ₃的PV性能。/ Ag，分别显示出4.2和7.31％的光转换效率。与热蒸发的金属对电极（例如Au和Ag）相反，此处将溶液中旋涂的Ag膜用作顶部触点，从而提高了成本效益和金属电极的制造障碍。