Water-Induced Formation of alpha-MoO3 Microcrystals as Anode Buffer Layer for Highly Efficient Polymer Solar Cells

Interfacial modification is an effective method to improve the performance of polymer solar cells (PSCs), and molybdenum oxide is one of the most widely used anode buffer layer (ABL) materials in PSCs. However, the complicated preparations with high-temperature annealing or vacuum deposition make it uneconomic. Herein, a facile method to prepare MoOx solution in 1-hexanol is proposed, and the component of the product can be simply adjusted by controlling the amount of introduced water. The added water facilitates the generation of alpha-MoO3 microcrystals. To the best of our knowledge, this is also the first report to obtain alpha-MoO3 through such a simple method. The obtained MoOx solutions are utilized to fabricate ABL in high efficiency PSCs to improve the performance. High temperature treatment is omitted, while the PCEs of binary and ternary devices can be enhanced to 16.09% and 16.81%, respectively, significantly higher than the devices with PEDOT:PSS ABL (15.55% and 15.93%). Herein, an efficient method to prepare MoOx solution in 1-hexanol with controlled component is offered, and it is demonstrated that the MoOx ABL derived from the MoOx solution is a potential replacement to enhance the performance of high efficiency PSCs.