A bismuth silver pnictohalide alternative to perovskite in fully-printable triple-mesoscopic solar cells

Abstract

Recent Ag₃BiI₆ solar cells have demonstrated promising efficiency, however, most have focused on mesoporous n-i-p configuration, using expensive hole transport materials (e.g., P3HT, PTAA and spiro-OMeTAD) and a Au counter electrode. To lower the cost and potentially enable larger scale Ag₃BiI₆ solar cells, herein, this study provides the first feasibility examination of Ag₃BiI₆ in fully-printable triple-mesoscopic (TiO₂/ZrO₂/carbon) solar cells (TM-SCs) and explores the effect of pre-treatment with small molecules and post-treatment (CuSCN) on the overall Ag₃BiI₆ TM-SC performance. An Ag₃BiI₆ solar cell with a power conversion efficiency (PCE) of 0.38% (J_sc = 1.97 mA cm⁻²; V_oc = 0.49 V; fill factor = 0.39) is demonstrated under 1 sun irradiation with two-month dark-storage stability in the ambient atmosphere. An improved V_oc from 0.43 V to 0.48 V was observed with biPY pre-treatment; a champion PCE of 0.74% (J_sc = 2.78 mA cm⁻²; V_oc = 0.56 V; fill factor = 0.48) was achieved with CuSCN post-treatment. The results reported here represent a step toward developing all inorganic Bi-based absorbers in printable TM-SCs, suggesting that further improvements should be possible with porous surface engineering and efficient charge extraction.