Flexible and semi-transparent perovskite solar cells

Abstract

Organic-inorganic hybrid perovskite solar cells have experienced a skyrocketing photoelectric conversion efficiency (PCE) increase in recent years, and become the “rock star” in the field of solar cells. After only 4 years, the certificated PCE of these materials based solid state solar cells have reach the maximum 22.1%, which is comparable to the highest PCE of the commercial silicon-based solar cells and higher than those of the organic solar cells and the dye-sensitized solar cells. Besides the promising efficiency, these materials surpass its competitors with the adaptability to solution- process at low-temperature and in air, and better flexibility, which can lead to lower large-scale production cost and more application potential for wearable electronics. The outstanding device performance of the hybrid perovskite solar cells have attracted intensive research interest, and besides increasing the PCE, lots of efforts have been focused on functional diversification for this solar cells. Compare to the commercial solar cells based on rigid silicon, organic- inorganic hybrid perovskite materials exhibit better flexibility which is beneficial for applications in flexible electronic devices, and due to the mild preparation conditions and the solution processablity, it is easy to prepare a variety of nanostructures. Those advantages have expanded the application scope of the hybrid perovskite materials, especially for fabricating flexible and semi-transparent solar cells which have potential use in building integrated photovoltaic such as solar cell windows and solar cell curtains. Here in this review, we focus on the recent progress of the flexible and semi-transparent solar cells based on organic-inorganic hybrid perovskite materials. In the part of the flexible hybrid perovskite solar cells, two mainstream device structures, namely planar and fiber-shaped devices, are discussed and the device structure and materials selection are analyzed in detail. As for the planar flexible perovskite solar cells, the choosing of the low-temperature processable function materials for the solar cells seems to be one of key factors due to the fact that most flexible planar substrates are vulnerable to the high-temperature treatments. As for the fiber-shaped perovskite solar cells, the choosing of the proper transparent conductive electrode materials is crucial which should have a good balance between the transparency and conductivity, and due to the difficulty of forming high-quality perovskite function layer on the curved surface of a certain wire, the prepare methods have to be upgraded too. In the part of the semi-transparent hybrid perovskite solar cells, two main strategies (reducing film thickness and forming isolated island structure) are discussed and a lot of reported preparation methods are analyzed in detail. As for the former strategy of reducing film thickness, the advantages are the comparatively higher PCE, easier manufacture and better controllability and the disadvantage is the unfavorable brownish color. As for the latter strategy of forming isolated island structure, the advantage is the better full-spectrum transmission and the disadvantages are comparatively more complicated manufacture and worse controllability. The whole paper has presented the development of the flexible and semi-transparent perovskite solar cells so far and gave detailed discussions for the reported works. Based on these analyzations, the organic-inorganic hybrid perovskites will find their special and unique position in the field of flexible and semi-transparent solar cells and may aggressively push the field forward.