Can Vacuum Deposition Apply to Bismuth-Doped γ-CsPbI₃ Perovskite? Revealing the Role of Bi³⁺ in the Formation of Black Phase

Abstract

The B-site doped CsPbI3 has been demonstrated to be very promising for photovoltaics owing to its low black phase transition temperature. Though B-site doped black-CsPbI3 perovskites have been successfully achieved by solution-processing, it is unclear whether these systems are available by other methods such as vacuum deposition. In this work, heterovalent doped CsPb1–x Bi x I3 is targeted. To incorporate Bi3+ into the final film via vacuum deposition, the solid solution precursor Pb1–x Bi x I2 (0.01 ≤ x ≤ 0.04) is developed. However, these coevaporated films not only are dominated by another hexagonal perovskite phase but also fail to decrease the black phase transition temperature. The role of Bi3+ in the formation of the black phase is further studied by solution methods with different types of precursors. It is demonstrated that the key factor in the low-temperature black phase transition is small grain size, as well as the colloid size within the precursor solution, rather than simple substitution of Pb2+ with Bi3+.

The high open-circuit voltage of perovskite solar cells: a review

“…As the adjacent element to Pb in the periodic table, the trivalent Bi 3+ cation has a similar electronic configuration and ionic radius to Pb and Sn, and therefore has been used to partly substitute the Pb 2+ cation at the B sites of lead perovskites. 184,185,306 For example, in an earlier study, Bi 3+ doping of CsPbI 3 was reported to improve the performance of CsPbI 3 solar cells although a recent study found that the Bi 3+ doped CsPbI 3 is not a thermodynamically favored system despite its better tolerance factor. 185 Pure Bi 3+ -occupied B site, neutral perovskites with the formula ABX 3 (A = Cs, MA; X = I, Br, Cl) are not possible because of the +3 valence state.…”

“…184,185,306 For example, in an earlier study, Bi 3+ doping of CsPbI 3 was reported to improve the performance of CsPbI 3 solar cells although a recent study found that the Bi 3+ doped CsPbI 3 is not a thermodynamically favored system despite its better tolerance factor. 185 Pure Bi 3+ -occupied B site, neutral perovskites with the formula ABX 3 (A = Cs, MA; X = I, Br, Cl) are not possible because of the +3 valence state. 306 Instead, CsPbI 3 forms ternary Bi 3+ -based perovskites that exist in structures with the formula A 3 Bi 2 X 9 (A = MA + , Cs + or Ag + , and X = I À or Br À ), where three Pb 2+ ions are replaced by two Bi 3+ ions to maintain the charge neutrality, and they form a 2D or 0D structure with face-sharing octahedra, unlike 3D CsPbI 3 or MAPbI 3 perovskite that exist in corner-sharing octahedra.…”

“…However, a recent work proposed that CsPb 0.96 Bi 0.04 I 3 is not a thermodynamically favored black phase system, though it has a larger τ . 185 CsPb 0.96 Bi 0.04 I 3 with compositional disorder and crystal strain can transform into Cs 4 PbI 6 under activation with enough thermal energy. Hence, the stabilization of the CsPbI 3 black phase by Bi 3+ incorporation can be mainly because of the tailored colloid size in the solvent system.…”

Phase transition mechanism of CsPbI2Br perovskite films induced by moisture

“…Frolova et al fabricated a 2D heterojunction CsPbI 3 perovskite cell achieving a power conversion efficiency of 10.5%, which was very close to the CH 3 NH 3 PbI 3based solar cell at that time [18]. The black cubic phase CsPbI 3 with a band gap of 1.73 eV is suitable for use as an absorption layer in photovoltaic devices [19][20][21][22][23]. However, only when the temperature exceeds ∼300 • C can CsPbI 3 maintain the stable black phase, while it should turn into an insulating yellow quadrature phase just in a few minutes at room temperature [24].…”

Reducing damage of sputtering and improving conductivity of transparent electrodes for efficient semi-transparent perovskite solar cells

“…Organic-inorganic halide perovskite solar cells have attracted wide attention due to their low cost, easy preparation and excellent photoelectric performance [1][2][3][4][5][6][7][8][9]. The conversion efficiency of single-junction perovskite solar cells has increased from 3.8% in 2009 to 25.7% in 2023 [10,11].…”