In this work, the effects of annealing temperature and time for one-step fabrication of mixed metal halide perovskite films were investigated. The photovoltaic performance of perovskite solar cells (PSCs) improved from 8.30 to 10.85% after being annealed at 100 degrees C for 10min and exhibited negligible photocurrent hysteresis when prepared at an ambient humidity of 70%. Besides, a high annealing temperature for a short time (150 degrees C; 1min) shows comparable power conversion efficiency with perovskite annealed at 100 degrees C for 10min. The electronic properties of PSCs were characterized by photo induced charge extraction via linearly increasing the voltage (photo-CELIV), impedance, and intensity modulated photovoltage spectroscopy. Our finding suggests that the improvement in photovoltaic performance is correlated to the improved charge mobility, suppressed charge trapping, and prolonged recombination lifetime.