Sodium Benzenesulfonate Modified Poly (3,4-Ethylenedioxythiophene):Polystyrene Sulfonate with Improved Wettability and Work Function for Efficient and Stable Perovskite Solar Cells

The p-type conducting polymer poly (3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) is widely utilized as the hole transport layer (HTL) for solution-processed planar perovskite solar cells (PSCs) with a p-i-n structure. However, the inverted PSCs based on PEDOT:PSS HTL suffer from deficient open-circuit voltage (V-OC) and poor stability issues, because of the high electron affinity and acid nature of PEDOT:PSS. Herein, sodium benzenesulfonate (C6H5SO3Na) (SBS) is applied to modify the PEDOT:PSS (SBS-PEDOT:PSS) layer to form a smoother surface and better energy-level alignment with the perovskite layer. In addition, the SBS-PEDOT:PSS layer with improved hole extraction capacity and suppressed charge recombination, significantly increases the grain size and crystallinity of the MA(0.8)FA(0.2)PbI(3-x)Cl(x) perovskite film. Consequently, the power conversion efficiency (PCE) and V-OC of the inverted PSCs are improved from 18.07% and 1.04 V to 19.41% and 1.08 V, respectively, after SBS modification. Moreover, the efficiency of the unencapsulated PSCs based on SBS-PEDOT:PSS remains above 90% after storing in ambient condition for 20 days. This research provides an accessible route to surmount the intrinsic imperfection of PEDOT:PSS and ameliorate the performance of PSCs.

Automated summary

In this research, the addition of sodium benzenesulfonate (SBS) to modify PEDOT:PSS layer improved the performance of perovskite solar cells (PSCs) by enhancing energy-level alignment, reducing charge recombination, and increasing grain size and crystallinity of the perovskite film. This modification led to an increase in the power conversion efficiency (PCE) and open-circuit voltage (V-OC) of the inverted PSCs. Furthermore, the unencapsulated PSCs remained highly efficient even after 20 days of storage in ambient conditions.