Multifunctional Buried Interface Modification Enables Efficient Tin Perovskite Solar Cells

Abstract

Tin perovskite solar cells (PSCs) are considered promising candidates to promote lead‐free perovskite photovoltaics. However, their power conversion efficiency (PCE) is limited by the easy oxidation of Sn2+ and low quality of tin perovskite film. Herein, an ultra‐thin 1‐carboxymethyl‐3‐methylimidazolium chloride (ImAcCl) layer is used to modify the buried interface in tin PSCs, which can induce multifunctional improvements and remarkably enhance the PCE. The carboxylate group (CO) and the hydrogen bond donor (NH) in ImAcCl can interact with tin perovskites, thus significantly suppressing the oxidation of Sn2+ and reducing the trap density in perovskite films. The interfacial roughness is reduced, which contributes to a high‐quality tin perovskite film with increased crystallinity and compactness. In addition, the buried interface modification can modulate the crystal dimensionality, favoring the formation of large bulk‐like crystals instead of low‐dimensional ones in tin perovskite films. Therefore, the charge carrier transport is effectively promoted and the charge carrier recombination is suppressed. Eventually, tin PSCs show a remarkably enhanced PCE from 10.12% to 12.08%. This work highlights the importance of buried interface engineering and provides an effective way to realize efficient tin PSCs.

Fabrication of Highly Luminescent Quasi Two-Dimensional CsPbBr3 Perovskite Films in High Humidity Air for Light-Emitting Diodes

“…The energy level diagram is given in Figure S10, showing that the 2PACz possesses better energy matching with perovskite than the PEDOT:PSS (−5.0 eV) and MeO-2PACz (−5.3 eV). 41,42 This result suggests that the hole injection can be more sufficient in the 2PACz-based PeLED compared with the PEDOT:PSS-and MeO-2PACz-based ones, which could contribute to balancing the injection of electrons and holes, thus benefitting the efficiency and stability of PeLEDs. Though the performance of PeLEDs is effectively improved by using 2PACz as the HTL, the exposed surface of perovskite to ambient air still remains problematic, which could accelerate water invasion, resulting in increased defect density and nonradiative recombination, which is unfavorable for the LED performance.…”

Modulating Nucleation and Crystal Growth of Tin Perovskite Films for Efficient Solar Cells

“…The N−H stretch peak of urea shifts from 3431.3 to 3425.6 cm −1 at the presence of SnI 2 , indicating the formation of the hydrogen bond of N−H•••I. 25 The presence of the hydrogen bond is also confirmed by the liquid-state 1 H nuclear magnetic resonance ( 1 H NMR) results in Figure S2, where the resonance signal at 5.43 ppm assigned to the N−H group is shifted to 5.53 ppm and widened upon mixing with SnI 2 . 26 Meanwhile, a shift from 1679.2 to 1674.8 cm −1 is observed for the C�O stretch peak in urea, implying the interaction between the C�O group in urea with the uncoordinated Sn 2+ .…”

Electronically Manipulated Molecular Strategy Enabling Highly Efficient Tin Perovskite Photovoltaics

“…This approach not only enables precise control over the buried surface characteristics to improve interfacial compatibility but also allows for interaction with the perovskite layer, enabling the regulation of crystallization processes or film passivation. [11][12][13][14] In the realm of buried interface modification research, the selection of the buried layer varies due to the diversity kinds of perovskite and the distinct structure of devices, whether in a normal or inverted structure. For instance, in lead PSCs, the prevalent choice for the n-i-p structure involves TiO 2 /perovskite and SnO 2 /perovskite interfaces, [15,16] whereas p-i-n devices opt for poly(bis(4phenyl) (2,4,6-trimethylphenyl) amine) (PTAA)/perovskite or Self-Assembly Material (SAM)/perovskite interfaces.…”

“…Buried interface modification is one feasible approach to address the issues. This approach not only enables precise control over the buried surface characteristics to improve interfacial compatibility but also allows for interaction with the perovskite layer, enabling the regulation of crystallization processes or film passivation [11–14] . In the realm of buried interface modification research, the selection of the buried layer varies due to the diversity kinds of perovskite and the distinct structure of devices, whether in a normal or inverted structure.…”