Light‐Triggered Sustainable Defect‐Passivation for Stable Perovskite Photovoltaics

Abstract

The generation of photoinduced defects and freely moving halogen ions is dynamically updated in real time. Accordingly, most reported strategies are static and short‐term, which make their improvements in photostability very limited. Therefore, seeking new passivation strategies to match the dynamic characteristics of defect generation is very urgent. Without newly generated defects, a passivation molecule should exist in the configuration that would not become the initiation sites for defect generation. With newly generated defects, the passivation molecule should transfer into the other configuration that possesses the passivation sites. Herein, a classical photoisomeric molecule, spiropyran, is adopted, whose pre‐ and post‐isomeric forms meet the requirements for two different configurations, to realize the state transition once the photoinduced defects appear during subsequent operation and dynamic capture for continuous renewal of defects. Consequently, spiropyrans work as light‐triggered and self‐healing sustainable passivation sites to realize continuous defect repair. The target devices retain 93% and 99% of their initial power conversion efficiencies after 456 h aging under ultraviolet illumination and 1200 h aging under full‐spectrum illumination, respectively. This work provides a novel concept of sustainable passivation strategy to realize continuous defect‐passivation and film‐healing in perovskite photovoltaics.

Anti-corrosion strategy to improve the stability of perovskite solar cells

“…105 DAE (C 18 H 19 NO 2 S 2 ), through molecular isomerism, can repeatedly invert between open and closed-ring isomers, reaching kinetic equilibrium states (state I and state II) via absorbing UV (365 nm) and visible light (>500 nm), and sustaining UV on/off cycling in the precursor solution, and thus, it is capable of providing long-term light stable and sustainable UV protection to devices. 105 Later, Wang et al 106 developed a sustainable dynamic passivation method for PSCs by adopting the photoisomeric molecule spiropyran. Our group 107 monitored the reversible phase-transition process of FA-dominated perovskites, namely δ-to-α phase (heat healing) and α-to-δ phase (humidity aging).…”

Iodide/triiodide redox shuttle-based additives for high-performance perovskite solar cells by simultaneously passivating the cation and anion defects

“…41 In particular, metal/organic halide salt additives such as NaX, CsX, KX, RbX, MAX, and FAX (where X = F, Cl, Br) have been added in to the precursor solution and/or the lattice of halide perovskites, showing two main functions: (1) cations with a suitable radius can occupy the A-site to stabilize the perovskite structure and adjust its band gaps and photoelectric properties and (2) anions anchor Pb 2+ through hydrogen bonds to inhibit the movement and immigration of Pb 2+ cations. 42 On the other hand, the surface modification of perovskite films aims to passivate grain boundaries and/or surface defects, forming a protective layer and constructing well-matched energy levels for PSCs. 43,44 It should be noted that most of the used additives and surface modifiers are sacrificial agents nowadays, which are not able to continuously passivate the newly formed defects during the operation of PSCs.…”

“…Several sustainably utilized agents have attracted significant attention for removing the regenerated defects, which would be beneficial for promoting the lifetimes of PSCs. 42,45,46 For instance, Shi et al introduced spiropyran molecules as a capping layer on the perovskite film, which incessantly passivated the renewable Pb vacancies in FAPbI 3 -based PSCs, leading to much improved PCEs and long-term stability under sunlight illumination. 42 In another work, Wang et al reported that the Eu 3+ /Eu 2+ redox pair could continuously oxidize Pb 0 and reduce I 0 defects circularly in FAPbI 3 -based PSCs to achieve enhanced PCEs and operational durability.…”

“…42,45,46 For instance, Shi et al introduced spiropyran molecules as a capping layer on the perovskite film, which incessantly passivated the renewable Pb vacancies in FAPbI 3 -based PSCs, leading to much improved PCEs and long-term stability under sunlight illumination. 42 In another work, Wang et al reported that the Eu 3+ /Eu 2+ redox pair could continuously oxidize Pb 0 and reduce I 0 defects circularly in FAPbI 3 -based PSCs to achieve enhanced PCEs and operational durability. 41 Similarly, the introduction of tributyl phosphine (TBUP)/tributyl phosphine oxide (TBPO) redox couples could efficiently reduce the concentrations of Pb 0 and I 0 defects in the fabrication processes and the operational conditions of FAPbI 3 -based PSCs, significantly improving the thermal stability.…”

Molecular modification of MAPbI3 surface: insights from first-principles theory studies

“…Shi et al reported that the transition between the pre- and post-isomeric forms could dynamically capture continuous renewal of defects, thus realizing continuous defect repair. 16 Kim et al reported a dual-side modification layer, poly-BCP, between the electron transport layer and PVK layer. The polymerized alkyl chain bridges could enable a uniform film structure and thus result in excellent transport characteristics.…”