The performance of all OPVs were measured using a Sun 2000 Solar Simulator (Abet Technologies) without any additional masking at room temperature. Calibration for 1 sun illumination (AM1.5G, 100 mW cm -2 ) was performed with a certified RS-OD4 reference silicon diode. Reverse and forward J-V sweeps between -0.1 V and 1.1 V were collected at a scan rate of 100 mV s -1 over 20 mV steps, with a Keithley 2635 source meter. The shutter was switched on for dark J-V measurements. The active area of each device (~0.5 × 0.5 cm 2 ) was measured manually.