Perovskite Solar Cells

Boosting Tunable Blue Luminescence of Halide Perovskite Nanoplatelets through Postsynthetic Surface Trap Repair

“…Halide perovskites in the form of bulk thin films have attracted significant interest owing to rapid rises in photovoltaic efficiencies. [1][2][3][4][5] Nanocrystals (NCs) of the same material have been garnering strong interest since 2014 for light emission applications due to high photoluminescence quantum yields (PLQYs) approaching unity and an emission wavelength that is tunable throughout the visible range by changing the halide ion. [6][7][8][9][10][11][12][13][14] Two of the important limitations currently hindering the widespread use of this material, are i) a very low efficiency of chloride-containing perovskite NCs, and thus only poor performance in the blue spectral range and ii) a tendency of mixed-halide perovskite to phase segregate into domains with different halide ion contents and resulting bandgaps, consequently shifting the emission wavelength strongly during operation of LEDs.…”

“…Halide perovskites in the form of bulk thin films have attracted significant interest owing to rapid rises in photovoltaic efficiencies. − Nanocrystals (NCs) of the same material have been garnering strong interest since 2014 for light emission applications due to high photoluminescence quantum yields (PLQYs) approaching unity and an emission wavelength that is tunable throughout the visible range by changing the halide ion. − Two of the important limitations currently hindering the widespread use of this material are (i) a very low efficiency of chloride-containing perovskite NCs, and thus only poor performance in the blue spectral range, and (ii) a tendency of mixed-halide perovskite to phase segregate into domains with different halide ion contents and resulting bandgaps, consequently shifting the emission wavelength strongly during operation of LEDs. − While most of these NCs are either bulklike or only weakly confined, several studies have shown strong quantum confinement in perovskite NCs as a further viable method to tune the emission wavelength especially toward the blue spectral range. − In particular, two-dimensional (2D) nanoplatelets (NPls) have been demonstrated with an atomic-precision control over their thickness down to a single monolayer (ML) and large exciton binding energies, an appealing characteristic for light-emitting applications. ,− These NPls are unfortunately strongly susceptible to surface defects due to a large surface-to-volume ratio, rendering their QYs typically quite low. ,,,, It was often observed that the PLQY of both hybrid and inorganic perovskite NCs drastically decreases with the change in morphology from cubic to platelet form. ,,, For instance, the PLQY of CsPbBr 3 NCs drops from 78% to 31% with a change of morphology from cubic to thick NPls. , Additionally, it is difficult to produce NPls of only a single thickness using current synthesis routes, and the resulting NPls tend to have problems with long-term stability. ,,− …”

Pathways for solar photovoltaics

“…27 and 28) in less than 3 years of development. [59][60][61] The term "perovskite" refers to the ABX 3 crystal structure, and the most widely investigated perovskite for solar cells is the hybrid organic-inorganic lead halide CH 3 NH 3 -Pb(I,Cl,Br) 3 . Optical bandgaps can be tuned from $1.25 to 3.0 eV by cation (A, B) or anion (X) substitution (e.g., HC(NH 2 ) 2 -Pb(I 1Àx Br x ) 3 , 62 CH 3 NH 3 SnI 3 , 63,64 and CH 3 NH 3 Pb(I 1Àx Br x ) 3 (ref.…”

Performance and stability of hybrid organic-inorganic perovskite photovoltaics in outdoor illuminations conditions

“…Perovskites have ABX 3 crystal structure where A is monovalent cation (usually Cs+, MA+, and FA+), B represents divalent cation (usually Pb 2+ or Sn 2+ ), and X represents halide anion (I − , Br − , Cl − ). The structural stability of the perovskite is determined by tolerance factor [12][13][14][15][16][17]. The tolerance factor suggests that the variable radii within the thin film perovskite layer may induce morphology imperfections.…”