PEDOT:PSS doping strategy of improving both interface energy level matching and photocarrier transport in FASnI₃ perovskite solar cells

Tin-based perovskite solar cells (PSCs) have been the focus of substantial research globally as a promising choice for lead-free PSCs. Sn-based PSCs performance, however, the performance of PSCs is still significantly inferior to that of lead-based PSCs. The disparity between the energy band levels of the perovskite absorber and charge transport layers, as well as the chemical instability of Sn halide perovskite crystals, are the primary constraints in this regard. Herein, potassium chloride (KCl) was added to polymer poly (3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) to improve the ability to transport holes and match energy levels. The formamidinium tin triiodide based PSCs constructed on KCl-doped PEDOT:PSS has a 5.9 % power conversion efficacy with a low hysteresis, which is comparatively higher than of the control devices (4.3 %). The improvement in photovoltaic performance has been predominantly attributed to two effects, specifically; PEDOT: PSS conductivity and hole extraction, both of which improved following KCl doping. More intriguingly, the modified device exhibit increased open-circuit voltage due to the downshift of PEDOT:PSS energy level by KCl doping. The composite hole transport layer strategy described in this paper provides a means for energy level adjustment and charge transport to enhance the performance of Sn-based PSCs.