原子层沉积金属氧化物缓冲层制备高性能大面积钙钛矿太阳电池

Preparation of high-performance large-area perovskite solar cells by atomic layer deposition of metal oxide buffer layer

研制具有较大活性面积的钙钛矿太阳电池对领域面向产业化的发展具有重要意义.当前,大面积钙钛矿太阳电池的性能与小面积钙钛矿太阳电池之间仍存在较大差距.本文提出一种在透明导电薄膜衬底上预先原子层沉积TiO_(2)薄层的策略,有效避免了衬底局部突起与钙钛矿吸光层直接接触导致的漏电现象,提升了小面积器件制备工艺的重复一致性.改善的电子输运和光管理过程也提高了小面积器件的效率.更重要的是,本文基于原子层沉积的TiO_(2)开展了0.5 cm^(2)大面积钙钛矿太阳电池的研究,通过优化TiO_(2)层的厚度,研制出光电转换效率高达24.8%的冠军器件(第三方认证效率24.65%),器件的制备工艺也表现出较好的重复性.此外,原子层沉积了TiO_(2)缓冲层的电池器件在氮气氛围下存储1500 h后仍然能够保留初始性能的95%以上.总之,在粗糙衬底上预先原子层沉积TiO_(2)薄层可以有效抑制局部漏电通道的产生,有利于制备高性能的大面积钙钛矿太阳电池.

Perovskite solar cells have been widely recognized as the most promising new-type photovoltaic device due to its power conversion efficiency rapidly increasing from 3.8%to over 26%in merely fifteen years.However,the high performances are achieved mainly on small area cells with an active area lower than 0.1 cm^(2).When enlarging the active area of perovskite solar cells,the efficiency falls dramatically.So,how to reduce the gap between performances of small area cells and large area cells gradually becomes a critical point in the path towards the commercialization of perovskite photovoltaic technology.Herein,a strategy of pre-growing thin layer of TiO_(2) on a rough FTO substrate by atomic layer deposition method before spin-coating SnO_(2) nanoparticles is proposed.Due to the inherent conformal film growth mode of atomic layer deposition,the FTO substrate can be completely covered by TiO_(2),thus preventing the direct contact between local protrusions of FTO and perovskite layer and impeding the current leakage phenomenon,which can be verified by the measurements from X-ray photoelectron spectroscopy,scanning electron microscopy,and atomic force microscopy,and further proved by the dark current measurement.By using this method,the repeatability and consistency of the small area cell fabrication technology on the same substrate are improved obviously.The improved electron transport process revealed by photoluminescence results and incident light management process revealed by external quantum efficiency results also brings about better solar cell performances.More importantly,highly efficient 0.5 cm^(2) large area perovskite solar cells are fabricated through optimization of TiO_(2) thickness.When growing 200 cycles TiO_(2)(~9 nm in thickness)by using atomic layer deposition technology,the champion large area perovskite solar cell possesses a power conversion efficiency as high as 24.8%(certified 24.65%).The device performances also show excellent repeatability between different fabrication batches.The perovskite solar cell with TiO_(2) buffer layer grown by the atomic layer deposition method can still retain over 95%of its initial efficiency after having been stored in a nitrogen atmosphere for 1500 h.The technique proposed in this paper can be helpful in manufacturing perovskite solar cell modules in the realistic photovoltaic market and can be extended to the large area fabrication of other perovskite optoelectronic devices such as light emitting diode,laser and detector.