Multidimensional Function Upgradation of All‐Inorganic CsPbIBr₂ Perovskite Film by Doping an Ionic Additive for Carbon–Electrode‐Based Solar Cells

Abstract

All‐inorganic CsPbIBr2 perovskite solar cells (PSCs) recently demonstrated great superiority for application in tandem and semitransparent photovoltaics because of their excellent phase stability. However, compared to state‐of‐the‐art PSCs, the inferior film quality is harmful for the photovoltaic performance improvement. Herein, a novel ionic additive, tetrabutylammonium hexafluorophosphate (TBAPF6), is employed to improve the all‐inorganic CsPbIBr2 perovskite film quality and passivate detrimental defects. By assembly into carbon–electrode‐based solar cells, a champion efficiency as high as 10.57% is achieved, which is much higher than that of a control device with 8.30% efficiency, mainly attributed to the suppressed non‐radiative recombination. More importantly, the presence of alkyl chains and fluorine atoms in TBAPF6 significantly increases the hydrophobicity of perovskite films and therefore improves the long‐term stability under harsh conditions without encapsulation.

Trimethyl Ammonium‐Assisted Interfacial Modification for Efficient and Stable Wide‐Bandgap Perovskite Solar Cells

“…The ideality factor of the optimal HTAB‐1 device is closer to 1 under open‐circuit conditions (1.34 vs 2.04 in Figure 3c) and short‐circuit (0.996 vs 0.987 in Figure S10, Supporting Information) than the pristine device, further ensuring the reduction of bimolecular recombination and trap‐assisted recombination by plotting the dependence of J SC and V OC on light intensity. [ 48 ] Furthermore, as shown in Figure 3d, the built‐in potential ( V bi ) was conducted from the classical Mott–Schottky (M–S) relation under dark condition. The HTAB‐1 device exhibits a larger slope (dashed lines) and a 40 mV higher V bi of 1.35 V than that of the pristine device (1.31 V) evidently demonstrating the increased interfacial driving force of charge carrier separation and drift, which, in turn, delivers an improved V OC due to the accelerated interfacial charge transfer at the CsPbIBr 2 /carbon surface of the HTAB‐1 device.…”

Limitations and Progresses in Carbon‐Based Cesium Lead Halide Perovskite Solar Cells

“…In an investigation, tetrabutylammonium hexafluorophosphate (TBAPF 6 ) was explored as an additive. [89] The results indicate that the TBAPF 6 benefited from regulating the crystallization process, resulting in an enlarged perovskite grain size and larger surface coverage. In addition, TBA + cations could passivate surface defects via electrostatic interaction.…”

Recent advances in ionic molecules applied in perovskite solar cells

“…Cho et al added the ammonium halide salt M-P chloride to form a chloride-rich intermediate phase in the precursor, retarding the nucleation rate and enlarging the grain Fig. 14 Chemical structures of MAB, BAFa, 104 MAAc, phenylurea, 105,143 DMII, 106 OMIMCl, 107 TBAPF 6 , 108 [C1CNmim]Cl, [C3CNmim]Cl and [(C3CN) 2 im]Cl. 110 size from B250 nm to B470 nm.…”

“…107 Zheng et al reported that with an IL additive TBAPF 6 , PF 6 − anions could partially substitute the halide ions and chelate Pb 2+ cations, which was beneficial to slow down the crystal growth. 108 In addition, the alkyl chain in TBA + may also alter the crystallization, enabling an enlarged perovskite grain size with improved surface coverage. Biberger studied in situ perovskite growth after solution-dropping, observing the fast formation of solvent-complex phases, which were gradually transformed to perovskite phases.…”