Harnessing solar energy with NH4Cl-doped hole transport layers in inverted perovskite solar cells

Abstract

Inverted perovskite solar cells have received enormous attention due to exceptional photovoltaic performance, yet they are susceptible to hysteresis and low conductivity. Poly 3,4-ethylenedioxythiophene: Poly 4-styrenesulfonate (PEDOT: PSS) is a widely utilized material in inverted perovskite solar cells as hole transporting layers. However, the low conductivity of the PEDOT: PSS is a significant hurdle toward high power conversion efficiency. Herein, we report an efficient and straightforward approach to modify the intrinsic properties of PEDOT: PSS via doping various amounts of ammonium chloride (NH₄Cl). Systematic observations have explored a significant transformation in the intrinsic properties of NH₄Cl doped PEDOT: PSS, resulting in higher conductivity compared with pristine PEDOT: PSS. The optimized NH₄Cl doped PEDOT: PSS exhibits higher surface roughness which not only improves the contact area between the active layer and the anode layer but also enhances the spectral absorption with a subsequent increase in the light-harvesting ability. As a result, the optimized NH₄Cl doped PEDOT: PSS delivers a superior power conversion efficiency (PCE), an open circuit voltage (V_OC), a short circuit current density (J_SC), and a fill factor (FF) of 17.5%, 1.02 V, 26.4 mA cm⁻¹ and 79.7%, respectively. We believe that this study will offer profound insights into the efficient and cost-effective synthesis of high-power conversion efficiency inverted perovskite solar cells.