Citric acid modified semi-embedded silver nanowires/colorless polyimide transparent conductive substrates for efficient flexible perovskite solar cells

Flexible solar cells, with the merits of structure compactness and shape transformation, are promising power sources for future electronic devices. However, frangible indium tin oxide-based transparent conductive substrates severely limit the flexibility of solar cells. Herein, we develop a flexible transparent conductive substrate of silver nanowires semi-embedded in colorless polyimide (denoted as AgNWs/cPI) via a simple and effective substrate transfer method. A homogeneous and well-connected AgNW conductive network can be constructed through modulating the silver nanowire suspension with citric acid. As a result, the prepared AgNWs/cPI shows low sheet resistance of about 21.3 ohm sq.(-1), high transmittance at 550 nm of 94%, and smooth morphology with the peak-to-valley roughness value of 6.5 nm. The perovskite solar cells (PSCs) on AgNWs/cPI exhibit power conversion efficiency of 14.98% with negligible hysteresis. Moreover, the fabricated PSCs maintain nearly 90% initial efficiency after bending for 2000 cycles. This study sheds light on the importance of suspension modification for the distribution and connection of AgNWs and paves a way for the development of high-performance flexible PSCs for practical applications.

Automated summary

Flexible solar cells have the potential to be an ideal power source for future electronic devices due to their compact structure and adaptable shape. However, the limited flexibility of these cells is caused by the delicate indium tin oxide-based transparent conductive substrates. In this study, a flexible transparent conductive substrate made of silver nanowires embedded in colorless polyimide was developed using a simple and effective transfer method. The resulting substrate showed a well-connected silver nanowire conductive network with low sheet resistance, high transmittance, and smooth morphology. The perovskite solar cells fabricated on this substrate exhibited high efficiency and maintained their initial efficiency after numerous bending cycles. This research highlights the importance of suspension modification for the distribution and connection of silver nanowires and opens up possibilities for high-performance flexible solar cells for practical applications.