Hydrazide Derivatives for Defect Passivation in Pure CsPbI₃ Perovskite Solar Cells

Abstract

All-inorganic CsPbI 3 perovskite presents preeminent chemical stability and a desirable band gap as the front absorber for perovskite/silicon tandem solar cells. Unfortunately, CsPbI 3 perovskite solar cells (PSCs) still show low efficiency due to high density of defects in solution-prepared CsPbI 3 films. Herein, three kinds of hydrazide derivatives (benzoyl hydrazine (BH), formohydrazide (FH) and benzamide (BA)) are designed to reduce the defect density and stabilize the phase of CsPbI 3 . Calculation and characterization results corroborate that the carboxyl and hydrazine groups in BH form strong chemical bonds with Pb 2 + ions, resulting in synergetic double coordination. In addition, the hydrazine group in the BH also forms a hydrogen bond with iodine to assist the coordination. Consequently, a high efficiency of 20.47 % is achieved, which is the highest PCE among all pure CsPbI 3 -based PSCs reported to date. In addition, an unencapsulated device showed excellent stability in ambient air.Since a cesium lead iodide (CsPbI 3 ) perovskite solar cell (PSC) was first reported in 2015, CsPbI 3 perovskite has attracted great interest due to its excellent chemical stability and appropriate band gap ( � 1.7 eV) as the front sub-cell active layer for tandem solar cells. [1][2][3] Regrettably, the highest power conversion efficiency (PCE) of CsPbI 3 -based

A Universal Grain “Cage” to Suppress Halide Segregation of Mixed-Halide Inorganic Perovskite Solar Cells

“…As evidenced from the XPS spectra of CsPbIBr 2 films in Figures g and S12, the shift of Pb 4f core levels to lower binding energies indicated the increased electron cloud density around the Pb atom. This is mainly attributed to the multiactive-site coordination effect between electron-donating N atoms (negatively charged centers marked in red in the electrostatic potential mapping image of structural repeating unit of COFs, as shown in Figures h and S13) and under-coordinated Pb 2+ species . Consequently, the N atoms with Lewis base feature would take up the vacancies within the perovskite matrix to improve the formation energy ( E F ) of V I from 0.139 to 0.936 eV (Figure i) based on density functional theory (DFT) calculation.…”

“…This is mainly attributed to the multiactive-site coordination effect between electron-donating N atoms (negatively charged centers marked in red in the electrostatic potential mapping image of structural repeating unit of COFs, as shown in Figures 2h and S13) and undercoordinated Pb 2+ species. 34 Consequently, the N atoms with Lewis base feature would take up the vacancies within the perovskite matrix to improve the formation energy (E F ) of V I from 0.139 to 0.936 eV (Figure 2i) based on density functional theory (DFT) calculation. As a result, the V I concentration is significantly reduced to approach the ion-to-vacancy and ionto-ion migration channels, which can be cross-checked by calculating activation energies of iodine ion migration at various points (nos.…”

Anchoring Vertical Dipole to Enable Efficient Charge Extraction for High‐Performance Perovskite Solar Cells

“…It is noted that the stretching vibration of C=O bond shifted from 1660 cm −1 in pure OI complexes (CL‐CH 3 , CL‐CF 3 ) to a lower wavenumber of 1643 cm −1 for the PbI 2 +CL‐CH 3 and PbI 2 +CL‐CF 3 samples, suggesting an interaction between PbI 2 and –C=O group in OI complexes. [ 32 , 33 , 34 ] Further, X‐ray photoelectron spectroscopy (XPS) was adopted to analyze the chemical compositions and environments of the perovskite films. The appearance of Os, P, and F characteristic peaks shown in Figure S14 (Supporting Information) indicates the existence of OI complexes in the final film.…”

LiF-Modified SnO2 Electron Transport Layer Improves the Performance of Carbon-Based All-Inorganic CsPbIBr2 Perovskite Solar Cells

“…PSCs have been widely given attention because of their simple preparation process, high carrier mobility, and large absorption coefficients. − The PCE of organic–inorganic hybrid PSCs has vastly jumped from 3.8% to a certified value of 25.7% within one decade. − However, due to the easy decomposition of the organic composition, it has instability in high-humidity and high-oxygen environments. − The traditional device structure of organic–inorganic PSCs typically uses a high-cost metal electrode and expensive organic hole transport layer (HTL), which limit commercial production to some extent. − Therefore, in pursuit of PSCs with good stability, low costs, and non-toxic nature, carbon-based all-inorganic PSCs have become a new research hot spot. − …”