Improving efficiency of inverted perovskite solar cells via ethanolamine-doped PEDOT:PSS as hole transport layer

In order to fabricate high-performance inverted perovskite solar cells(Pe SCs), an appropriate hole transport layer(HTL) is essential since it will affect the hole extraction at perovskite/HTL interface and determine the crystallization quality of the subsequent perovskite films. Herein, a facile and simple method is developed by adding ethanolamine(ETA)into poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS) as HTL. The doping of a low-concentration ETA can efficiently modify the electrical properties of the PEDOT:PSS film and lower the highest occupied molecular orbital(HOMO) level, which is more suitable for the hole extraction from the perovskite to HTL. Besides, ETA-doped PEDOT:PSS will create a perovskite film with larger grain size and higher crystallinity. Hence, the results show that the open-circuit voltage of the device increases from 0.99 V to 1.06 V, and the corresponding power conversion efficiency(PCE)increases from 14.68% to 19.16%. The alkaline nature of ethanolamine greatly neutralizes the acidity of PEDOT:PSS, and plays a role in protecting the anode, leading the stability of the devices to be improved significantly. After being stored for2000 h, the PCE of ETA-doped PEDOT:PSS devices can maintain 84.2% of the initial value, which is much higher than67.1% of undoped devices.