The ability of a light‐sensor to detect fast variation in incident light intensity is a vital feature
required in imaging and data transmission applications. Solution‐processed bulk
heterojunction (BHJ) type organic photodiodes (OPDs) have gone through key
developments, including dark current mitigation and longer linear dynamic range. In
contrast, there has been less focus on increasing OPD response speed (f–3dB). Here, bulk
heterojunction OPDs based on electron‐donating polymer poly [thiophene‐2, 5‐diyl‐alt‐5 …

Dark current (idark) from the OPD was measured under dark condition, as a function of time.
Through current-time scan, N number of different discrete dark-current values (idark, n) were
measured, the average of which is denoted by ̅̅̅̅̅̅. The noise or the fluctuations about
this average (Avg.) is determined by taking the root-of-mean-of-square (RMS) of the discrete
data points (idark, n) about the average (̅̅̅̅̅̅), as shown in Equation S1, and shown in
Figure S2 for case of OPD with 50wt% acceptor concentration under 0 V applied bias.