Pseudohalide Functional Additives in Tin Halide Perovskite for Efficient and Stable Pb-Free Perovskite Solar Cells

Abstract

The progress of tin-based halide perovskite solar cells (Sn-HaPSCs) is obstructed by their poor stability arising from tin oxidation. Herein, we introduced phenethylammonium thiocyanate (PEASCN) as a pseudohalide functional additive into an FASnI3 perovskite film to improve the optoelectronic properties. This approach is found to be effective for the suppression of Sn oxidation and formation of a compact and larger grain film with a higher degree of crystallinity. The device with the PEASCN additive improved the device efficiency from 4.52% (for pristine Sn-HaP) to 9.65% with a significant increase of VOC from ∼0.411 to 0.667 V and superior device stability. The device analysis revealed that the PEASCN additive has improved the optoelectronic properties coupled with a higher diffusion potential and suppression of bulk and interface defects in the Sn-HaPSC. This work corroborates that the incorporation of a pseudohalide-based functional additive in FASnI3 is propitious for better film formation, passivation of detrimental surface chemistry, and defects at the interface and in the bulk.

Interfacial Embedding for High‐Efficiency and Stable Methylammonium‐Free Perovskite Solar Cells with Fluoroarene Hydrazine

“…This observation is parallel to our earlier report on degradation with interfacial deterioration. [ 6 ] It also shows a sharp transition of M–S curves suggesting a narrower depletion layer capacitance ( C dl ) regime that could be related to low defect density. A saturated capacitance ( C s ) regime for V D is caused by charge accumulation at the interface and electrode polarization.…”

“…[ 1,2 ] However, this has imposed challenges for its practical application due to its lacking stability under heat and light stress as well as susceptibility to a humid atmosphere. [ 3–6 ] The surface passivation approach has been widely employed in PSCs to improve the device parameters as well as stability as a consequence of mitigating the defect activities, [ 7 ] modifying interfacial band alignments, [ 8 ] improving carrier extraction dynamics, [ 9 ] and enhancing moisture tolerability. [ 10,11 ]…”

Methylammonium and Bromide‐Free Tin‐Based Low Bandgap Perovskite Solar Cells

“…To improve the optoelectronic properties of FASnI 3 perovskite film, a pseudohalide functional additive phenethylammonium thiocyanate (PEASCN) has been utilized by Khadka et al. [ 104 ] With the PEASCN addition, the device's efficiency increased to 9.65% from 4.52%, with a considerable increase in V OC from 0.411 to 0.667 V. The calculated carrier profile from Capacitance–voltage ( C−V ) spectra is shown in Figure 5i. According to C − V analysis, the bulk carrier density (≈2.36 × 10 16 cm −3 ) was reduced (to ≈8.24 × 10 15 cm −3 ) for the film containing PEASCN additive.…”

“…i) Carrier profile of FASnI 3 devices without and with PEASCN additive, extracted from C-V analysis. Reproduced with permission [104]. Copyright 2021, American Chemical Society.…”

Sustainable development of perovskite solar cells: keeping a balance between toxicity and efficiency

“…Pseudohalide derivative additives are also used in PSCs to enhance their PCE and processing efficiency. 160–162 These additives are usually thiocyanate, a toxic substance that is slightly less toxic than cyanide but more difficult to degrade. 163 Thus, due to environmental and health concerns, caution is required with the use of AOX.…”