Ambient‐Air‐Stable Inverted Perovskite Solar Cells by Carbazole Analog Tailored Perovskite Thin Films

Abstract

Perovskite solar cells (PSCs) have aroused vast attention and achieved unprecedented development. However, commercial utilization requires better reliability while maintaining high efficiency. Typically, the uncoordinated band energy configuration and structural defects led to recombination, these bottlenecks have seriously damaged the device performance and limited the further development of PSCs. In addressing those questions, researchers have provided various countermeasures including doping to trim the band structure and solvent engineering to modify the crystallization process and introducing reduced dimensional perovskite to maintain long‐term stability. Herein, a convenient carbazole analog doping strategy is reported by adding a certain amount of bromide‐substituted carbazole analog in the perovskite precursor which succeeded in modifying the surface morphology and optimizing the bandgap structure of the film, additionally maintaining considerable stability. As a result, a champion power conversion energy (PCE) of 22.25% is reached and preserved 85% of the initial PCE while stored in ambient air for more than 1200 h (around 30% relative humidity), and with low hysteresis. A simple but practical doping strategy to fabricate efficient and stable perovskite films in ambient air is provided.

Imidazole-Based Ionic Liquid Engineering for Perovskite Solar Cells with High Efficiency and Excellent Stability

“…32 The N 1s peak (Figure 2e,f) decreased to a lower binding energy, suggesting that the additive may form an FA−cation−π interaction with FA + , thus reducing the binding energy. 33 The Pb 4f peak in Figure 2g shifts to a lower binding energy, which is associated with the electronic contribution of the BzMIM + cation. 34,35 Regarding the core level spectra of I 3d in Figure 2i, the binding energy peaks of I 3d1/2 and I 3d2/3 also demonstrate a discernible downward shift trend toward lower binding energies after modification, which is likely due to the formation of hydrogen bonds between the BzMIM + and I from perovskites.…”

“…The perovskite film doped with BzMIMBr existed a weak peak at 287.6 eV, indicating that BzMIM + can passivate bulk organic cations, effectively preventing the invasion of active ingredients and thus inhibiting the degradation of perovskite . The N 1s peak (Figure e,f) decreased to a lower binding energy, suggesting that the additive may form an FA–cation−π interaction with FA + , thus reducing the binding energy . The Pb 4f peak in Figure g shifts to a lower binding energy, which is associated with the electronic contribution of the BzMIM + cation. , Regarding the core level spectra of I 3d in Figure i, the binding energy peaks of I 3d1/2 and I 3d2/3 also demonstrate a discernible downward shift trend toward lower binding energies after modification, which is likely due to the formation of hydrogen bonds between the BzMIM + and I from perovskites. , The strong coupling effect between Cs + vacancies and amino functional groups enhanced the Cs signal (Figure i) .…”

Stable and Efficient Inverted Perovskite Solar Cells Enabled by Structural Design of Lewis Base Molecules

“…In the PSC based on the M2-passivated MAPb(I 0.97 Br 0.03 ) 3 thin film, the V TFL of electrons and holes are 0.52 and 0.54 V, respectively, which are better than those of the PSC based on the M1passivated MAPb(I 0.97 Br 0.03 ) 3 thin film and PSC based on the MAPb(I 0.97 Br 0.03 ) 3 thin film. We then calculated the hole/ electron defect density of states for the PSCs thin films, which can be estimated using the following equation: 54 N V eL 2 t 0 TFL 2 (7) where ε 0 is the vacuum permittivity ( S6 gives the external quantum efficiency (EQE) of PSCs based on MAPb(I 0.97 Br 0.03 ) 3 thin films and M1 and M2 passivated MAPb(I 0.97 Br 0.03 ) 3 thin films. PSCs based on MAPb(I 0.97 Br 0.03 ) 3 thin films and M1-and M2-passivated MAPb(I 0.97 Br 0.03 ) 3 thin films show a photocurrent response up to 750 nm, which is consistent with the UV−vis absorption spectrum (Figure 3c).…”

“…This also indicates that the nonradiative composite loss of the PSC based on M2-passivated MAPb(I 0.97 Br 0.03 ) 3 thin film is greatly suppressed, and the carrier mobility is enhanced. The charge carrier mobility can be obtained using Mott–Gurney law: J = 9 ε 0 ε μ 0 V 2 8 L 3 where V is the external bias applied in the PSC, μ 0 is the charge carrier mobility, ε 0 is the vacuum permittivity (8.8542 × 10 –12 F/m), ε is the corresponding permittivity of MAPbI 3 (approaches 40), L denotes the perovskite thin film thickness (considered as 400 nm), and J is the current density.…”

“…In the PSC based on the M2-passivated MAPb(I 0.97 Br 0.03 ) 3 thin film, the V TFL of electrons and holes are 0.52 and 0.54 V, respectively, which are better than those of the PSC based on the M1-passivated MAPb(I 0.97 Br 0.03 ) 3 thin film and PSC based on the MAPb(I 0.97 Br 0.03 ) 3 thin film. We then calculated the hole/electron defect density of states for the PSCs thin films, which can be estimated using the following equation: N t = 2 ε 0 ε V TFL e L 2 where ε 0 is the vacuum permittivity (8.8542 × 10 –12 F/m), e is the primitive charge (1.6 × 10 –19 C), ε is the corresponding permittivity of MAPbI 3 (approaches 40), and L denotes the perovskite thin film thickness (400 nm). The calculated defect densities for MAPb(I 0.97 Br 0.03 ) 3 thin films passivated by M1 and M2, and unpassivated MAPb(I 0.97 Br 0.03 ) 3 thin film are listed in Table .…”