Alumina nanoparticles enable optimal spray-coated perovskite thin film growth on self-assembled monolayers for efficient and reproducible photovoltaics

The power conversion efficiencies of metal halide perovskite photovoltaics have increased rapidly over the past decade attracting significant academic and industrial interest. The ease with which high performance perovskite photovoltaics can be fabricated through solution processing routes has opened up significant possibilities for fabrication through existing, industrially mature high-throughput solution coating techniques such as spray-coating. The power conversion efficiencies of spray-coated metal halide perovskite photovoltaics are limited by non-radiative recombination at the interfaces with charge transport layers necessitating the implementation of new charge transport layers. The self-assembled monolayer (SAM) charge transport layers have resulted in record perovskite photovoltaic device performances, due to reduced non-radiative recombination. However, poor wettability associated with some SAMs significantly limits their applicability, this is exaggerated for droplet-based scalable technologies like spray-coating. Here we report an optimised aluminium oxide nanoparticle interlayer which enables spray-coating of triple cation metal halide perovskite thin films and devices onto Me-4PACz (([4-(3,6-dimethyl-9H-carbazol-9-yl)butyl]phosphonic acid). Our interlayer results in improved structural and optoelectronic properties of spray-coated perovskite thin films, compared to those fabricated through spin-coating. These improved properties enable the fabrication of p-i-n photovoltaic devices with efficiencies over 20 % - some of the highest reported for both spray-coated devices in p-i-n architecture, and devices having a spray-coated “triple cation” perovskite active layer.

金属卤化物钙钛矿光伏的功率转换效率在过去十年中迅速提升，引起了学术界和工业界的广泛关注。通过溶液处理途径轻松制备高性能钙钛矿光伏器件的可能性，为利用现有的、成熟的工业级高通量溶液涂层技术，如喷涂技术，提供了广阔的制造前景。喷涂法制备的金属卤化物钙钛矿光伏的功率转换效率受限于电荷传输层界面的非辐射复合，这促使新的电荷传输层的应用。自组装单分子层（SAM）电荷传输层由于降低了非辐射复合，从而实现了钙钛矿光伏器件性能的突破性提升。然而，与某些SAM相关的较差润湿性显著限制了其适用性，这在基于液滴的规模化技术如喷涂技术中尤为明显。在本研究中，我们报告了一种优化的氧化铝纳米粒子中间层，它使得在Me-4PACz（[4-(3,6-二甲基-9H-咔唑-9-基)丁基]磷酸）上喷涂三阳离子金属卤化物钙钛矿薄膜和器件成为可能。我们的中间层相较于旋涂法制备的钙钛矿薄膜，在结构和光电性能方面均有显著提升，这些提升的性能使得制备p-i-n光伏器件成为可能，其效率超过20%，这在喷涂器件在p-i-n结构中的报道中属于较高水平，同时也包括具有喷涂“三阳离子”钙钛矿活性层的器件。