Supplemental Material Numerical simulation: Toward the design of high-efficiency perovskite planar solar cells Feng Liu,1 Jun Zhu,1 Junfeng Wei,1 Yi Li,1 Mei Lv,1 Shangfeng Yang,2 Bing Zhang,3 Jianxi Yao,3 and Songyuan Dai1,3 1 Key Laboratory of Novel Thin Film Solar Cells, Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, Hefei, 230031, P. R. China 2 Hefei National Laboratory for Physical Sciences at Microscale, Department of Materials Science and Engineering, University of Science and Technology of China, Hefei, 230026, P. R. China 3 State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing, 102206, P. R. China 1. The Poisson equation (1), hole continuity equation (2) and electron continuity equation (3) are shown as follows: d dψ x q p( x) n(x) N d ( x) N a ( x) pt ( x) nt ( x) dx dx dpn p pn 0 dp d 2 pn dξ Gp n pnμ p μ p ξ n Dp dt τp dx dx dx 2 dn p dt Gn np np0 τn dn p d 2np dξ n pμ n + μ nξ Dn dx dx dx 2 (1) (2) (3) where ε is the permittivity and q the electron charge, G the generation rate and D the diffusion coefficient. ψ is the electrostatic potential and n, p, nt, pt are the free electron, free hole, trapped electron and trapped hole, respectively. N+d is the ionized donor-like doping concentration and N-a the ionized acceptor-like doping concentration. ξ is the electric field. 2. FIG. S1. Schematic diagram of the planar heterojunction-based perovskite solar cells. 3. TABLE S1. AMPS-1D parameters set for the baseline solar cells. Compact Parameters and units CH3NH3PbI3 TiO2 Dielectric Constant 1001 302 Band Gap (eV) 3.2 1.54 Electron Affinity (eV) 4 3.934 Thickness (nm) 90 400 0.006, Electron and Hole Mobility (cm2/V/S) 50, 506 0.0061 Acceptor Concentration (cm-3) 0 (2.14×1017)4 Donor Concentration (cm-3) (5×1019)1 0 Effective Conduction Band Density (1×1021)9 (2.5×1020)4 (cm-3) Effective Valence Band Density (cm-3) (2×1020)5 (2.5×1020)4 Characteristic Energy for Donor and (0.015, 0.01,0.01 Acceptor-Like Tails (eV) 0.015)10 3 14 Band Tail Density of States(1/cm /eV) 1×10 1×1014 Capture Aross Section for Electrons and 1×10-15, 1×10-15, Holes in Donor Tail States (cm2) 1×10-17 1×10-17 Capture Cross Section for Electrons and 1×10-17, 1×10-17, Holes in Acceptor Tail States (cm2) 1×10-15 1×10-15 Gaussian Defects Donor and Acceptor 1×1017, 1×1014, State Density (cm-3) 1×1017 1×1014 Gaussian Defects Donor and Acceptor 1.1, 1.1 1.2, 1.2 Peak Energy (eV) Standard Deviation (eV) 0.1, 0.1 0.1, 0.1 Capture Cross Section of Donor-Like 1×10-19, 1×10-20, Gaussian State for Electron and Holes 1×10-18 1×10-19 (cm2) Capture Cross Section of Acceptor-Like 1×10-18, 1×10-19, Gaussian State for Electron and Holes 1×10-19 1×10-20 (cm2) Spiro-MeOTAD 33 2.915 2.25 400 0.0001, 0.00017 (3×1018)8 0 2.5×1020 2.5×1020 0.01, 0.01 1×1014 1×10-15, 1×10-17 1×10-17, 1×10-15 1×1016, 1×1016 1.1, 1.1 0.1, 0.1 1×10-19, 1×10-18 1×10-18, 1×10-19 Left and right contact work function: -4.4 eV (FTO) and -5.1 eV (Au), respectively. Ohmic contact with surface recombination speed of electrons and holes: 1×107 cm/s. 4. FIG. S2. J-V curves of the solar cells that result from the numerical simulation with parameters set in Table S1. 5. FIG. S3. Effective absorption coefficient of the CH3NH3PbI3 films (derived from Ref. 10). 6. TABLE S2. Parameters set for the thin inserted layer. Layer at the TiO2/CH3NH3PbI3 Parameters and units interface Dielectric Constant 302 Band Gap (eV) 1.54 Electron Affinity (eV) 3.934 Thickness (nm) 4 2 Electron and Hole Mobility (cm /V/S) 50, 506 Acceptor Concentration (cm-3) (2.14×1017)4 Donor Concentration (cm-3) 0 -3 Effective Conduction Band Density (cm ) (2.5×1020)4 Effective Valence Band Density (cm-3) (2.5×1020)4 Characteristic Energy for Donor and (0.015, 0.015)10 Acceptor-Like Tails (eV) Band Tail Density of States(1/cm3/eV) Capture Aross Section for Electrons and Holes in Donor Tail States (cm2) Capture Cross Section for Electrons and Holes in Acceptor Tail States (cm2) Switch-Over Energy (eV) Density of Midgap Acceptor and Donor-Like States (cm-3eV-1) Capture Cross Section of Electrons and Holes in Donor Midgap States (cm2) Capture Cross Section of Electrons and Holes in Acceptor Midgap States (cm2) 1×1014 1×10-15, 1×10-17 1×10-17, 1×10-15 0.7 1×1016 to 1×1021 1×10-17, 1×10-18 1×10-18, 1×10-17 Reference 1 K. 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