Figure 5

Solar-cell performance and trap-density characterization. (a) J−V curves at both reverse and forward voltage scans. The blue dashed line represents the highest efficient cell. (b) Incident photon-to-current conversion efficiency (IPCE). (c) Frequency dependent capacitances (C(ω) ≡ Real [{iωZ(ω)}−1]) obtained from the impedance analysis. (d) Trap density of states as a function of trap level with respect to the valance-band maximum, from Eqs (1) and (2). The dashed lines denote Gaussian fitting for the calculation of traps per volume (nt). All the perovskite films are annealed at 120 °C for 600 s.