Engineering of P3CT-Na through diprophylline treatment to realize efficient and stable inverted perovskite solar cells

Abstract

Poly[3-(4-carboxybutyl) thiophene-2,5-diyl] (P3CT) is extensively used as hole transport layers (HTL) for efficient inverted perovskite solar cells (PSCs). However, some drawbacks of P3CT-Na such as strong aggregation tendency and unwell-matched energy alignment restrict the application of P3CT-Na-based devices. Here, diprophylline is first used to modify the P3CT-Na HTL in inverted PSCs. Diprophylline modifies work function of ITO (indium tin oxide) by self-assembling onto the ITO surface. Meanwhile, it could interact with P3CT-Na through hydrogen bonding interaction, thus inducing ordered arrangement of P3CT-Na molecules, and increasing transmittance of the HTL. In addition, diprophylline could partially dissolve into the upper perovskite layer, and facilitate the perovskite crystallization. As a result, inverted PSCs utilizing diprophylline added P3CT-Na as HTL yield a remarkable efficiency of 20.87% and excellent long-term stability. Notably, the fill factor (FF) is approaching 84%, representing one of the highest results in inverted PSCs. More interestingly, when the diprophylline treated P3CT-Na layer undergoes ultrasonic cleaning in deionized water for 10 mins, the as-fabricated PSCs still show a high efficiency of 18.77%, manifesting good durability of the HTL. Thus, the recyclability and cost-effectiveness of the HTL makes it more applicable in future commercialization. This work provides a new strategy of improving efficiency and long-term stability of inverted PSCs through HTL engineering.