The furrowed hole-transport layer using Argon plasma in the inverted perovskite solar cell
In invert perovskite solar cell, Poly (3,4-ethylene dioxythiophene) (PEDOT) and poly(styrene sulfonate) (PSS) are traditional hole transition materials which the function improvement are getting hard for the device. However, in this study, a novel process is found to be effective using Argon-plasma treatment, which the ion cluster scours PEDOT:PSS surface instead of the traditional bombing method. By an ideal plasma-generation powers and treatment times (1800 J), the largest photoelectric conversion efficiency (PCE) of the device of PED (PEDOT:PSS surface being parallel to the plasma-generation electric field direction ) reaches 14.8%, an improvement of 23.3%, compared to VED (vertical to the plasma electric field direction) device whose PCE is 13.31%, while the reference is 12.0%. As the physics mechanism, both PED and VED treatment can increases the surface free energy and roughness to result in a suitable hydrophilicity and large grain size of the perovskite film. Because the ratio of PEDOT and PSS is changed by plasma treatment, the conductivity of the film is also increased observably. Furthermore, because PED has the furrowing effect on the PEDOT:PSS surface, the ordered crystallization leads to few pinholes perovskite film and make the above mentioned properties better than VED.