Piperazine Suppresses Self-Doping in CsSnI₃ Perovskite Solar Cells

Abstract

Tin-based halide perovskite materials are promising candidates for lead-free halide perovskite solar cells. However, they suffer from poor device reproducibility and limited overall power conversion efficiencies due to their tendency to become semimetallic from p-type defect states. Herein, we demonstrate an effective approach to address this issue via the addition of piperazine to the precursor solution of tin-based halide perovskite films, to suppress the undesirable p-doping of CsSnI 3 films. Piperazine is found to significantly reduce the conductivity of CsSnI 3 films, improve the film coverage, and at the same time suppress the crystallization of excess SnI 2 . Consequently, shortcircuit behaviors are eliminated, with significantly improved CsSnI 3 solar-cell performance. Moreover, the effects of incorporating SnCl 2 and SnF 2 into the CsSnI 3 devices were investigated in conjunction with addition of piperazine to achieve CsSnI 3 devices with a maximum power conversion efficiency of 3.83%.

A Two‐Step Modified Sequential Deposition Method‐based Pb‐Free (CH3NH3)3Sb2I9 Perovskite with Improved Open Circuit Voltage and Performance

“…have employed FASnI 3 (FA= NH 2 CHNH 2 ) perovskite and obtained a PCE of 7.94 % which was further jumped to 8.17 % by Kim et al . Further, Song et al . and Heo et al .…”

“…[15] Therefore, Snaith and co-workers have investigated the optoelectronic properties of CH 3 NH 3 SnI 3 perovskite and employed it as light absorber. The developed PSCs exhibited an interesting PCE of 6 % [15] which further improved to 7.13 % by Li et al [16] In another work, Liu et al [17] have employed FASnI 3 (FA = NH 2 CHNH 2 ) perovskite and obtained a PCE of 7.94 % which was further jumped to 8.17 % by Kim et al [18] Further, Song et al [19] and Heo et al [20] also used another Pb-free CsSnI 3 perovskite and achieved the PCE of 3.83 % and 4.31 % respectively. Gupta et al investigated the optoelectronic properties of CsSnBr 3 and employed as light absorber with the introduction of SnF 2 additive and obtained a PCE of 2.1 %.…”

Potential Substitutes for Replacement of Lead in Perovskite Solar Cells: A Review

“…The undesirable p‐doping of CsSnI 3 perovskite films can be reduced by the addition of piperazine that can improve the morphology of the film as well as can alleviate the crystallization of excess SnI 2 at the same time. With the use of piperazine as an additive, CsSnI 3 perovskite devices displayed a SPCE of 3.83% . Table 6 shows some photovoltaic parameters of cesium‐based perovskites.…”

Stability enhancement of lead‐free CsSnI3 perovskite photodetector with reductive ascorbic acid additive

“…Among them, SnF 2 does not bring about significant variation in lattice constants and unwanted phases . Besides, reducing vapor atmosphere process and organic additives are also considered to be effective ways to inhibit the oxidation of Sn 2+ in Sn‐based halide perovskite film . For instance, Kanatzidis et al constructed a hydrazine vapor atmosphere to optimize the quality of the perovskite film and realized a power conversion efficiency (PCE) of 1.83% for CsSnI 3 solar cell .…”