Formation of stable 2D methylammonium antimony iodide phase for lead-free perovskite-like solar cells^*

Abstract

The presence of lead in novel hybrid perovskite-based solar cells remains a significant issue regarding commercial applications. Therefore, antimony-based perovskite-like A 3 M 2 X 9 structures are promising new candidates for low toxicity photovoltaic applications. So far, MA 3 Sb 2 I 9 was reported to only crystallize in the 'zero-dimensional' (0D) dimer structure with wide indirect bandgap properties. However, the formation of the 2D layered polymorph is more suitable for solar cell applications due to its expected direct and narrow bandgap. Here, we demonstrate the first synthesis of phase pure 2D layered MA 3 Sb 2 I 9 , based on antimony acetate dissolved in alcoholic solvents. Using in situ XRD methods, we confirm the stability of the layered phase towards high temperature, but the exposure to 75% relative humidity for several hours leads to a rearrangement of the phase with partial formation of the 0D structure. We investigated the electronic band structure and confirmed experimentally the presence of a semi-direct bandgap at around 2.1 eV. Our work shows that careful control of nucleation via processing conditions can provide access to promising perovskite-like phases for photovoltaic applications.

Lead‐Free Perovskite‐Inspired Absorbers for Indoor Photovoltaics

“…Although the i‐SLMEs of the 0D compound are low, recent work has shown that the 2D phase can be stabilized, leading to a near‐direct bandgap (which allows higher absorption coefficients) and a lower bandgap value of 2.1 eV (which is closer to the optimum for IPV). [ 84 ]…”

“…Although the i-SLMEs of the 0D compound are low, recent work has shown that the 2D phase can be stabilized, leading to a near-direct bandgap (which allows higher absorption coefficients) and a lower bandgap value of 2.1 eV (which is closer to the optimum for IPV). [84] InI is another material with high i-SLMEs of 53%. However, InI devices have demonstrated relatively poor 1-sun photovoltaic efficiencies of ≈0.4%.…”

2D/3D Hybrid Cs2AgBiBr6 Double Perovskite Solar Cells: Improved Energy Level Alignment for Higher Contact‐Selectivity and Large Open Circuit Voltage

“…[ 36 ] We note that although the bandgap is significantly underestimated, we can assume that the DFT‐PBE method provides accurate predictions about the electronic nature of the calculated structure. [ 60,61 ] Hence, a direct bandgap with an energy of 2.8 eV was obtained (Figure S11, Supporting Information), increasing the energy by 0.6 eV compared to the 3D Cs 2 AgBiBr 6 . [ 17 ]…”

Efficiency improvement for perovskite-inspired Cs3Sb2I9 solar cells using P3HT as the hole transport material

“…5 In particular, the 2D polymorph is more desirable for photovoltaics owing to the higher mobility and defect tolerance than the 0D counterpart. [6][7][8][9][10] Strictly speaking, Cs 3 Sb 2 I 9 is not a perovskite but a perovskite derivative or perovskite-inspired material. 11,12 In this paper, however, the term perovskite is in some occasion used broadly to cover also the perovskite derivatives.…”