Abstract This study investigates how different thicknesses of the electron transport layer (ETL) impact the performance of Formamidinium lead iodide (FAPbI 3 ) solar cells with a silver back contact. The solar cell structure includes a 200 nm-thick fluorine-doped tin oxide (FTO) window layer, a Formamidinium lead iodide layer for light absorption, and a tin(IV) oxide (SnO 2 ) layer serving as the ETL, with thicknesses of 5, 10, 15, and 20 nm. Using the spin-coating method with anti-solvent treatment, followed by annealing at 400 °C, solar cells were fabricated with and without the SnO 2 -perovskite absorber. Results show that the ETL thickness significantly affects key performance parameters, including charge transport, recombination, and overall efficiency. The perovskite solar cells featuring with 20 nm SnO 2 layer have a crystallite size of 40.1 nm. It also shows the lowest transmittance at 45 % and the highest absorption coefficient at 7.5 × 10 4 per cm. This material also has the highest refractive index of 2.2, the best conductivity of 0.55 × 10 −2 S/cm, and the lowest resistivity at 1.82 × 10 2 Ω cm. Moreover, the optical band gap decreases to 1.52 eV, resulting in a higher short-circuit current density (Jsc) of 23.5 mA/cm 2 and an open-circuit voltage (Voc) of 1.2 V. An optimum performance of perovskite solar cells featuring 20 nm SnO 2 is recommended for solar cell applications.
Kaliyaperumal et al. (2026) studied this question.