Improvement of the performance of carbon based all-inorganic perovskite solar cells by using ammonium acetate modified rutile TiO2 nanorods array as the electron transport layer

Carbon-based all-inorganic perovskite solar cells are currently emerging as a commercial and promising photovoltaic device . Rutile TiO 2 has the function of UV shielding and preventing the decomposition of perovskite, furthermore, TiO 2 nanorod array provides the direct 1-D electron transmission channel. Herein, vertically oriented rutile TiO 2 nanorods array are synthesized on the FTO substrate by a simple one-step hydrothermal process and used as the electron transfer layer. The analysis of characterization illustrates that the prepared TiO 2 is a flawless single rutile phase. TiO 2 nanorods are employed as an ETL to provide a passage for the rapid and direct charge transfer. The separation of electrons and holes can be enhanced by ammonium acetate treatment of the TiO 2 nanorod ETL/perovskite interface, and the carrier recombination can be efficiently lowered. Based on the structure of FTO/TiO 2 @CH 3 COONH 4 /CsPbI 2.25 Br 0.75 /C, the best device containing 2.5 mg/mL ammonium acetate modified TiO 2 nanorods showed a short-circuit current density of 14.55 mA/cm 2 , open-circuit voltage of 1.08 V, and fill factor of 69.45 %, yielding a power conversion efficiency of 11.53 %, which show an increase in efficiency of approximately 22.4% when compared with the control cell. The results show that ammonium acetate interface modification is an effective strategy to enhance the photovoltaic performance of PSCs.