Device fabrication for characterizing electrical doping
Fabrication of Perovskite Film:SiO2(270 nm-thick) on Si and glasswere used as substrates.
The substrates were sequentially sonicated inacetone, 2-propanol, and deionized water for 10 min each. Then, the Siand glass substrates were claned using O2 plasma treatment (200 mT,30 sccm, 50 W) for 120 sec. After dropping 100μL of precursor solution on the prepared substrate, the substrate was rotated at 500 rpm for 5 second then at 4000 rpm for 50 sec with a spin-coater, followed by drying in a nitrogen environment for 5 min and annealing at 100°C for 10 min to fabricate each perovskite filme
After covering the prepared BA2 PbI4 film with a shadow mask with a channel length of 50 μm and a width of 1 mm, an Au electrode with a thickness of 50 nm was deposited with an electron beam evaporator. Doping with dopant solution was performed by immersing the prepared film in the solution for 2 min. After taking out from the solution, the film was immediately spin-coated at 500 rpm for 5 sec and then at 4000 rpm for 50 sec, followed by drying in a nitrogen environment for 5 min.
Figure. 3 Device fabrication steps for electrically doped metal-halide perovskite by using immersion doping method.
Electrical Doping Characterization
Electrical Measurement:
- The I–Vcharacteristics were measured using a semiconductor parameter analyzer (Keithley 4200 SCS). All the measure-ments were performed in a vacuum environment.
- Hysteresis, due to ion migration and defects, causes nonlinear I-V curves in halide perovskites, limiting their practical use. To address this, different measurement ranges (0V-10V, -10V-10V, -20V-20V) were tested. The Tukey Test revealed that while average values differed pre and post-doping, conductance across sweep ranges was equivalent. By averaging currents under both forward and reverse biases, a linear I-V curve was achieved, with R-square values of 0.994 to 0.995. This suggests that, despite hysteresis, accurate conductivity values can still be obtained.
(a) Current–voltage characteristics (inset; optical microscope images of the films) (b) The measured conductance values presented in box and whisker diagram at each sweep range. The diagram on the right shows the Comparison circles obtained from the Tukey test. The comparison circles have their centers each aligned with the average conductance values and the radii proportional to the standard deviation values of each distribution. The more the comparison circles overlap, the more similar the distributions are.