Effect of CsCl Additive on the Morphological and Optoelectronic Properties of Formamidinium Lead Iodide Perovskite

Abstract

The quality of perovskite films plays a crucial role in improving the optoelectronic properties and performance of perovskite solar cells (PSCs). Herein, high‐quality CsxFA1−xPbI3 perovskite films with different compositions (x = 0, 5, 10, and 15) are achieved by controlling the amount of cesium chloride (CsCl) in the respective FAPbI3 precursor solution. The effects of CsCl addition on the morphological and optoelectronic properties of the resulting perovskite films and on the performance of the corresponding devices are systematically studied. Introduction of CsCl into FAPbI3 shows a great potential to stabilize the α‐FAPbI3 perovskite phase by forming CsxFA1−xPbI3 films with improved morphology and carrier lifetimes. With an optimal 10 mol% CsCl additive, the average power conversion efficiency (PCE) is increased from 16.83 ± 0.30% for the reference FAPbI3‐based PSCs to 18.87 ± 0.25% (with a steady‐state PCE of 18.89%). Moreover, the optimized device performance is more stable after 20 days than the controlled one under ≈40% humidity in air.

Two birds with one stone: dual grain-boundary and interface passivation enables >22% efficient inverted methylammonium-free perovskite solar cells

“…17,95 There is no signal related to a Cl 2p doublet at a binding energy of ~198.6 eV and ~200.2 eV despite using CsCl in the precursor solution which can be explained by the sublimation of FACl during the annealing process. 16,112,134 We note that we do not observe a peak related to metallic lead (Pb 0 ) at ~137 eV which emphasizes the high quality of our reference perovskite films. 19,20,74,87 Upon PEACl:PbCl 2 incorporation and/or PEACl surface treatment (GBP, SP and GBP&SP films) there are three key observations as compared to the Ref film.…”

Two Birds with One Stone: Dual Grain-Boundary and Interface Passivation Enables > 22% Efficient Inverted Methylammonium-Free Perovskite Solar Cells

“…17,95 There is no signal related to a Cl 2p doublet at a binding energy of B198.6 eV and B200.2 eV despite using CsCl in the precursor solution which can be explained by the sublimation of FACl during the annealing process. 16,112,134 We note that we do not observe a peak related to metallic lead (Pb 0 ) at B137 eV which emphasizes the high quality of our reference perovskite films. 19,20,74,87 Upon PEACl:PbCl 2 incorporation and/or PEACl surface treatment (GBP, SP and GBP&SP films) there are three key observations as compared to the Ref film.…”

Mesoscopic TiO2/Nb2O5 Electron Transfer Layer for Efficient and Stable Perovskite Solar Cells

“…In this work, we employ MA‐free perovskite with the composition of Cs 0.1 FA 0.9 PbI 3 as an absorber active layer. [ 48 ] The devices were composed of 30 nm thick compact TiO 2 layer, 150–180 nm thick mesoporous TiO 2 layer, 400 nm thick perovskite layer, 200 nm thick Spiro‐OMeTAD as an HTL and 80 nm thick Au as an electrode (Figure S7, Supporting Information). The photocurrent density–voltage ( J–V ) curves measured under 1 Sun illumination at reverse scan for the devices with different thicknesses of Nb 2 O 5 are presented in Figure 2b and the corresponding PV parameters are listed in Table 1 .…”

“…[63] The ms-TiO 2 solution (1:6 weight ratio paste: ethanol) was deposited by spin-coating method onto the c-TiO 2 layer and calcined at 500 °C for 30 min. A perovskite precursor composition of FAPbI 3 with 10 mol% CsCl were spin coated on ms-TiO 2 at 1000 and 6000 rpm for 10 and 20 s. During the second step, 200 µL chlorobenzene was dropped on at 15 s. [48] The deposited film was annealed at 150 °C for 30 min to get perovskite light-absorption layer. Next, spiro-OMeTAD (0.0723 g mL −1 chlorobenzene) solution was spin coated on the perovskite layer at 4000 rpm for 30 s. The spiro-OMeTAD solution www.advmatinterfaces.de was prepared by adding TBP, Li-TFSI in acetonitrile, and FK209 in acetonitrile (molar ratio of spiro-OMeTAD : FK209 : Li-TFSI : TBP of 1 :0.03 : 0.5 : 3.3).…”