Improvement in Efficiency and Reproducibility for FAPbI₃ Solar Cells with Rapid Crystallization

Abstract

Clarifying the crystallization process of the perovskite FAPbI 3 film is quite an important pathway for improving the performance of perovskite solar cells, and the annealing time is a key factor to control the nucleation and crystal growth. However, the existing electrodeposition method lacks systematic studies on the growth of the perovskite FAPbI 3 film. Herein, we manipulate the annealing time precisely for growing a pure α-FAPbI 3 perovskite film in the electrodeposition-assisted method. The perovskite pure α-FAPbI 3 film can be synthesized by fast annealing in only 1 min, and the as-prepared perovskite film shows high solar light absorption capacity and large grains. Thus, the corresponding solar cells based on α-FAPbI 3 show the best power conversion efficiency (PCE) of 13.33%, which is 32% higher than that of FAPbI 3 solar cells annealed for a long time (20 min). More importantly, all of these PCE variances do not exceed 1% under different annealing times, indicating the high reproducibility of the perovskite solar cells based on this rapid crystallization method. With a phenethylammonium iodide passivation layer, the PCE can even be improved to 14.02%.

Multistep optimization for the electrodeposited mixed perovskite FA1−y Cs y PbBr x I3−x solar cells

“…Previous reports also demonstrate that the CsBr dopants can stabilize the black phase α-FAPbI 3 perovskite [34]. Figure S3 shows the XPS full survey spectra of the electrodeposited PbO 2 film, which is consistent with our previous reports [32]. To further improve the efficiency of the mixed perovskite FA 1−y Cs y PbBr x I 3−x solar cells, we manipulate the growth temperature for the reaction between PbO 2 and FAI with CsBr.…”

“…The electrolyte aqueous solution is composed of 0.1 M Pb (CH 3 COO) 2 , 0.1 M HNO 3 , 0.2 M NaNO 3 , and 0.05 M NaCl). Referring to our previous studies [31,32], the electrodeposition voltage is usually set as 1.5 V with a deposition time of 15 s. The thickness of the PbO 2 film is 177 ± 13 nm. After the PbO 2 film was deposited, it was immersed in the mixed FAI/ CsBr solution (25 * 25 cm weighing bottle) at room temperature, which contains 1 ml FAI/isopropanol solution (60 mg ml −1 ) with different amounts (5 μl, 20 μl, 40 μl, 80 μl) CsBr/methanol solution (8 mg ml −1 ).…”

“…For example, Huang et al acquired the MAPbI 3 film through the direct reaction between the electrodeposited PbO and spin-coated MAI, and the acquired MAPbI 3 solar cells display a high PCE of 14.59% [30]. Besides, the perovskite FAPbI 3 films can also be synthesized by the direct reaction of electrodeposited PbO 2 and spin-coated FAI [31,32], where the corresponding solar cells display an optimized PCE of 14.02%. From the abovementioned electrodeposition-based fabrication routes for perovskite solar cells, we can find that although there are some achievements have been obtained, it is apparent that electrodeposition methods for preparing perovskite solar cells are still a new emerging research field that requires deeper and systematic research to improve the efficiency of the perovskite solar cells.…”

Additive Engineering for Mixed Lead–Tin Narrow-Band-Gap Perovskite Solar Cells: Recent Advances and Perspectives

“…29−32 Therefore, the newly developed PSCs are considered as the most potential replacements to traditional silicon-based solar cells for large-scale and sustainable photovoltaic power generation. 33,34 Although the PCEs of Pb-based PSCs have reached 25.7% recently, the large-scale applications of Pb-based organic−inorganic hybrid PSCs still face many crucial challenges. 35−38 First, the band gaps of Pb-based organic− inorganic perovskites currently used in high-performance PSCs are generally 1.5−1.6 eV, which are much larger than the theoretical optimal band gap of 1.3−1.4 eV for solar cells calculated according to the Shockley−Queisser (S−Q) theory.…”

“…The new third-generation solar cells, such as perovskite solar cells (PSCs), dye-sensitized solar cells, and quantum dot solar cells, have received increasing interests recently as a result of the facile fabrication process, low-cost raw material, and superior theoretical PCEs. − In particular, PSCs with lead (Pb)-based halide perovskites as light absorbers exhibit several unique and excellent optical/electronic properties, including adjustable band gaps, high optical absorption coefficients, high mobility, and long diffusion length of charge carriers, leading to a rapid boosting rate of PCEs of PSCs from 3.8 to 25.7% in the last 14 years. − Therefore, the newly developed PSCs are considered as the most potential replacements to traditional silicon-based solar cells for large-scale and sustainable photovoltaic power generation. , Although the PCEs of Pb-based PSCs have reached 25.7% recently, the large-scale applications of Pb-based organic–inorganic hybrid PSCs still face many crucial challenges. − First, the band gaps of Pb-based organic–inorganic perovskites currently used in high-performance PSCs are generally 1.5–1.6 eV, which are much larger than the theoretical optimal band gap of 1.3–1.4 eV for solar cells calculated according to the Shockley–Queisser (S–Q) theory . Second, the toxicity of Pb is extremely harmful to the environment and humans. − To overcome these problems, numerous researchers are trying to develop new Pb-free or Pb-less halide perovskites using non-toxic metals, including tin (Sn), bismuth (Bi), and germanium (Ge), to achieve sustainable and clean perovskite photovoltaics. − Among various alternatives to Pb 2+ cations, Sn 2+ cations have similar electronic structures to Pb 2+ and comparable ion radii (the ionic radii of Sn 2+ and Pb 2+ are 110 and 119 pm, respectively). − Therefore, partial or complete replacement of Pb 2+ in perovskites by Sn 2+ will not lead to significant lattice distortions in the perovskite structure .…”