Intermediate‐Adduct‐Assisted Growth of Stable CsPbI₂Br Inorganic Perovskite Films for High‐Efficiency Semitransparent Solar Cells

Abstract

Thanks to the tunable bandgap and excellent photoelectric characteristics, perovskites have been widely used in semitransparent solar cells (ST‐SCs). Most works present unsatisfactory power conversion efficiencies (PCEs) through reducing the thickness of the perovskite films because there is a trade‐off between PCE and average visible transmittance (AVT). As a consequence, most PCEs are less than 12% when the AVT is higher than 20% due to the limited voltage (Voc) and short‐circuit current (Jsc). Herein, a strategy of intermediate adduct (IMAT) engineering is developed to improve the film quality of the inorganic perovskite CsPbI2Br, which is a challenging issue to limit its performance of efficiency and stability. A normal n–i–p‐structured PSC based on the optimal CsPbI2Br film delivers a PCE of 16.02% with excellent stability. Furthermore, through optimizing the electrode type and interface, the ST‐PSC shows a high Voc larger than 1.2 V and the PCE reaches 14.01% and 10.36% under an AVT of 31.7% and 40.9%, respectively. This is the first demonstration of a CsPbI2Br ST‐PSC, and it outperforms most of other types of perovskites.

Managing Defects Density and Interfacial Strain via Underlayer Engineering for Inverted CsPbI2Br Perovskite Solar Cells with All‐Layer Dopant‐Free

“…To better understand the interaction between TS‐CuPc‐i and perovskite, X‐ray photoelectron spectroscopy (XPS) analysis was performed on thin perovskite films, which could be prepared by depositing a diluted precursor solution (≈20 times) on the Spiro/TS‐CuPc‐i and Spiro‐OMeTAD substrates, respectively, followed by regular thermal annealing. [ 38 ] As shown in Figure 5d, the Pb 4f peaks are shifted by 0.50 eV to lower binding energy upon the introduction of TS‐CuPc‐i, which might be ascribed to the formation of Pb‐O coordination interaction between TS‐CuPc and perovskite. [ 39 ] In addition, the I 3d peaks are also shifted to lower binding energy by 0.44 eV (Figure 5e), presumably due to the electrostatic interaction between Na + cation of TS‐CuPc and iodine species in perovskite.…”

A Key 2D Intermediate Phase for Stable High‐Efficiency CsPbI2Br Perovskite Solar Cells

“…The recombination resistance ( R rec ) and capacitance ( C rec ) are determined by fitting these curves using an equivalent circuit model. [ 45 ] The LDIAG 0.5‐IMX CsPbI 2 Br device possesses a larger R rec than the control CsPbI 2 Br device (Table S4, Supporting Information). This indicates that the charge transfer was promoted and the charge recombination was restrained in the LDIAG 0.5‐IMX films.…”

Organic Matrix Assisted Low‐temperature Crystallization of Black Phase Inorganic Perovskites

“…[83] Inspired by the strong interaction between the C = Nb ond of the Schiff base and the metal ions in the perovskite structure,( chloromethylene)dimethylammonium chloride (CDCl) was utilized to improve the quality of CsPbI 2 Br films. [84] Thec rystallization took place through the formation of an intermediate adduct of PbI 2 •CsBr•CDCl, which yielded the final film with fewer trap states and suppressed recombination.…”

“…In terms of the first factor, the formation of intermediate states has always been aprevailing theory when investigating the crystallization mechanism of inorganic perovskite films. [62,84,88,97,99,117] As previously discussed, the addition of organic compounds,m any of which contain volatile components such as MA + and DMA + cations, [62,70,118] leads to the formation of highly unstable intermediates with perovskite structures at low temperatures.A ss hown schematically in Figure 7, the characteristics of the formed intermediate resemble those of organic-inorganic hybrid perovskites. During the annealing process,t he volatile organic components would sublimate and leave the structure,t hereby allowing Cs + ions to occupy the empty cation sites in the crystal lattice.S ince the composition and the stoichiometry between different ions in the intermediate can be tuned by the amount of organic additive in the precursor solution, the kinetics of the crystallization (or the rate and degree of Cs + entering the lattice) and thus the formation of the perovskite film can be well-controlled to achieve high quality and stability.…”