Carrier transport layer engineering of Cs2TiI2Br4 halide double perovskite solar cell via SCAPS 1D: Approaching the Shockley-Queisser limit

Abstract

All-inorganic Cs₂TiI_xBr_(6-x)-based perovskite solar cells (PSCs) are recently attracting a lot of attention for their tunable bandgaps, earth abundance, non-toxicity, and ultra-stability. Among the Cs₂TiI_xBr_(6-x) family of materials, Cs₂TiI₂Br₄ with a bandgap of ∼1.38 eV has the potential to be an excellent single junction solar cell material with a theoretically higher Shockley-Queisser limit of power conversion efficiency (PCE). Its excellent optoelectronic properties make it a potential candidate for being the highest-performing PSC from the Cs₂TiI_xBr_(6-x) family. In our study, a total of eight hole transport materials (P3HT, PTAA, Spiro-OMeTAD, PEDOT:Pss, CuSCN, CuI, NiO, and MoO₃) and six electron transport materials (PCBM, TiO₂, CdS, SnO₂, ZnO, and IGZO) were investigated to select suitable charge transport materials. The defect densities of interface and absorber, different absorber layer thicknesses, several metal work functions, series-shunt resistance, and temperature were investigated to derive the conditions for optimum performance. After thorough investigation, we derived four novel devices with the combination of all the organic and inorganic charge transport materials to provide optimum performance. Among them, the combination of inorganic SnO₂ and CuSCN as electron and hole transport layer respectively achieved the highest PCE of 23.41 %.