Performance improvement of perovskite solar cells using electron and hole transport layers

In this study, various electron and hole transport structures were created in perovskite solar cells to ameliorate the problem of carrier mobility balance. Balanced electron and hole mobilities could reduce carrier recombination probability in the cells to improve their performance. The space-charge-limited current (SCLC) method was used to calculate the electron and hole mobilities of perovskite devices with various electron transport layers (ETLs) and hole transport layers (HTLs). Compared with perovskite devices with [6,6]-phenyl-C-61-butyric acid methyl ester (PC₆₀BM) single ETL and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) single HTL, the current density and power-conversion efficiency of perovskite solar cells with [6,6]-phenyl-C-71-butyric acid methyl ester/pristine fullerenes (PC₇₀BM/C₇₀) dual ETLs and PEDOT:PSS/poly[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]-thiophenediyl] (PTB7) dual HTLs increased from 18.22 to 24.11 mA/cm² and 7.07% to 14.11%, respectively. Compared with the carrier mobility balance ratio (μ_h/μ_e) of 0.35 of perovskite solar cells with PC₆₀BM single ETL and PEDOT:PSS single HTL, perovskite solar cells with dual ETLs and dual HTLs showed a μ_h/μ_e of 0.90, which led to the performance improvement of the cells.