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Wang et al. Energy Mater. 2026, 6, 600064 Page 9 of 34

vulnerability is fundamentally rooted in a thermodynamic coupling effect. Qu et al. established that
[72]
adjacent anion and cation vacancies exhibit a mutual promotion mechanism in which the presence of one
defect significantly lowers the formation energy of the other. This intricate thermodynamic relationship
dictates that functional additives must achieve synergistic defect passivation rather than targeting single
defects. Cation vacancies severely disrupt the local charge balance and generate detrimental deep trap states.
Building upon the molecular locking concept previously introduced for lead passivation, researchers have
developed analogous synergistic systems to heal these cation vacancies. A representative example is the
all-organic molecular lock fluorinated anilinium benzylphosphonate (FABP), which consists of a
fluorophenylammonium cation and a fluorobenzyl phosphonate anion. The cation selectively occupies
vacant formamidinium or methylammonium sites while the anion simultaneously compensates for missing
halides. This dual action dramatically reduces trap density, suppresses non-radiative recombination, and
extends carrier lifetimes from approximately 4 ns to beyond the detection limit, accompanied by a
significantly improved PLQY . Following this synergistic principle, N-methylammonium formate
[70]
(NMACOOH) provides NMA to fill cation vacancies while its HCOO coordinates with Pb to effectively
-
+
2+
suppress non-radiative charge losses . In all-inorganic CsPbI systems, alkylammonium bromides such as
[71]
3
N,N,N-trimethyl-1-dodecanaminium bromide (DTABr) can heal Cs vacancies through the strong coupling
+
of their organic cations with the [PbI ] octahedra. Concurrently, the Br ions passivate lead-related defects
4-
-
6
to yield enhanced photoluminescence (PL) intensity and prolonged carrier lifetimes . For multifunctional
[98]
small molecules, 2-hydrazinylpyrazine (2-HZP) exemplifies this dual-site mechanism through extensive
hydrogen-bonding networks that increase the formation energy of FA-related vacancies while
simultaneously coordinating with undercoordinated Pb 2+[72] . Furthermore, polymeric additives demonstrate
superior multifunctional defect passivation capabilities, as exemplified by polyvinylpyrrolidone (PVP), which
simultaneously passivates both cation and anion vacancies through the coordinated interactions of its amide
group oxygen and nitrogen atoms. This comprehensive passivation mechanism effectively suppresses anion
exchange reactions and photoinduced halide segregation to enhance both the crystalline integrity and the
photovoltaic performance of the devices .
[99]
Antisite defects

Beyond the thermodynamic instability associated with ion vacancies, the perovskite lattice is equally
vulnerable to the misplacement of its constituent elements. Antisite defects arise when ions occupy incorrect
positions within the ABX framework, commonly manifesting as iodine on a lead site (I ) or lead on an
3
Pb
iodine site (Pb ). Because these misplaced species induce profound local charge imbalances and spatial
I
distortions, they readily generate detrimental deep-level trapping centers that degrade device performance.
To overcome these challenges, a widely adopted approach involves the introduction of tailored halide or
pseudohalide anions that can integrate into the lattice framework to heal these defects. Cheng et al. [100]
demonstrated that BF from potassium borofluoride (KBF ) interacts with I to transform deep defect levels
-
Pb
4
4
into shallow states, significantly reducing trap density. Likewise, Zhu et al. [101] introduced the ionic liquid
1-ethyl-3-methylimidazolium chloride (EMImCl) to show that Cl exhibits exceptionally low adsorption
-
energy (0.46 eV) on the (110) crystal plane, enabling incorporation into the superficial lattice and formation
of robust Pb-Cl and Cs-Cl bonds that effectively suppress Pb defects. Supplementing these inorganic anion
Br
strategies, researchers frequently employ specialized Lewis basic molecules and polydentate chelating agents
to firmly anchor the distorted lattice through organic coordination. Zhao et al. [102] developed a tridentate
ligand 1,10-phenanthroline-5-amine (PAA) in which two pyridyl nitrogens and one amino nitrogen
simultaneously coordinate with Pb to substantially elevate the formation energies of both I and V . This
2+
Pb
I
reduction in defect density is consistent with density of states (DOS) calculations indicating a more robust
crystalline framework. Similarly, Zhuang et al. [103] utilized diphenylguanidinium bromide (DPGABr) to
establish strong coordination between its -NH groups and Pb , which shifts the defect states induced by Pb I
2+
2