Application of arginine-doped PEDOT:PSS as a hole transfer layer in perovskite solar cells

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is employed as the hole transport material in inverted perovskite solar cells (PSCs) due to its good conductivity, uniform film formation, and low energy consumption. However, the presence of sulfonic acid groups in the PSS chains of PEDOT:PSS makes the solution acidic. Moreover, PEDOT:PSS as a hole transport layer (HTL) exhibits hygroscopicity and anisotropy, which can reduce the power conversion efficiency (PCE) and long-term stability of PSCs. Here, we employed arginine as an additive in the PEDOT:PSS solution to adjust the pH value of the PEDOT:PSS solution from 3.7 to 6.8. By incorporating arginine, the open-circuit voltage (Voc) of the PSCs increased from 0.92 V to 1.08 V, and the PCE improved from 15.06% to 17.35%. The enhancement of performance is attributed to the interaction between the amino groups in arginine and the sulfonic acid groups in the PSS chains, which reduces the acidity and surface roughness of PEDOT:PSS. This modification decreases the contact barrier between the perovskite layer and the HTL, enhances charge collection and transport capabilities, and thereby improves the PCE and long-term stability of the inverted PSCs. This study provides a new approach for the industrialization of perovskite solar cells. Arginine was employed as an additive in the PEDOT:PSS solution to facilitate the transformation of PSS-H to PSS-NH3, aiming to address the challenges associated with excessive acidity and substantial interface energy dissipation in the HTL.