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Wang et al. Energy Mater. 2026, 6, 600064 Page 5 of 34

enable a controlled ripening process that allows the perovskite layer to achieve high crystallinity and superior
morphological uniformity. Building on this foundation, strong Lewis-base donors such as dimethyl sulfoxide
(DMSO) and N-methyl-2-pyrrolidone (NMP) stabilize coordination complexes and intermediate phases by
forming stable PbI ·solvent adducts, which delay the α-phase transition and extend the solvent-release
2
window, thereby facilitating controlled crystallization and enhanced film quality [54,55] . This mechanism of
intermediate regulation is vividly demonstrated in slot-die-coated MAPbI inks processed with
3
2-methoxy-ethanol (2-ME). Within this system, a fundamental trade-off exists because the concentration of
DMSO must be precisely tuned to govern the competition among different solvated species. An optimal
amount of DMSO facilitates the formation of beneficial PbI ·DMSO or solvated iodoplumbate intermediates
2
that effectively suppress the emergence of undesirable MAPbI -2-ME crystalline phases . Insufficient
[56]
3
DMSO allows the formation of these deleterious solvated adducts that lead to high film porosity, whereas an
excessive concentration can result in the retention of overly stable complexes that hinder efficient conversion
into the perovskite lattice. Because these solvent-solute interactions directly dictate the kinetics of film drying
and the subsequent crystallization pathway, they have profound consequences for the final grain size and the
optoelectronic quality of the semiconductor layer. More sophisticated molecular additives offer a precise
route to overcome the inherent sensitivity of solvent-solute equilibria during film formation. Specifically, the
introduction of tris(2-benzimidazolylmethyl)amine (TR-2-BA) exemplifies how tailored intermolecular
interactions can steer the coordination environment of precursor inks . Through the formation of extensive
[57]
hydrogen-bonding and coordination networks with DMSO, TR-2-BA effectively suppresses the stochastic
formation of diverse solvated intermediates. This regulatory mechanism enforces the emergence of a singular
and uniform (FA) ·Pb I ·2DMSO intermediate phase that bypasses the stringent requirements of DMSO
3 8
2
stoichiometry previously discussed. Consequently, the homogenization of the intermediate phase ensures
highly consistent nucleation and growth behaviors across varying fabrication conditions, leading to
enhanced film reproducibility and significantly reduced defect densities in the resulting devices [Figure 1B].

Controlling grain coarsening and nucleation
Once a uniform and properly defined nucleation landscape is established, the subsequent phase of controlled
crystal growth can proceed as a natural consequence. To guarantee that this progression translates into a
high-quality thin film, additives must continue to function as kinetic regulators that prevent uncontrolled
grain coarsening and sporadic secondary nucleation. Without such regulation during the growth phase, the
expanding lattice remains susceptible to accumulating stress and forming non-radiative recombination
centers at grain boundaries. Feng et al. provided a compelling demonstration of this guided growth
[2]
paradigm by introducing 4,4′-oxydibenzenesulfonyl chloride (OBSC), a bifunctional additive featuring two
sulfonyl chloride groups on a flexible backbone. The unique spatial configuration of OBSC enables multisite
coordination by strongly binding to undercoordinated Pb through Pb-O interactions while simultaneously
2+
engaging formamidinium cations via hydrogen bonding. During the critical crystal growth phase, these
robust intermolecular interactions stabilize the perovskite and solvent intermediate phases to precisely
regulate the crystallization kinetics. This targeted molecular intervention effectively decelerates and
homogenizes the overall grain growth process, thereby passivating high-energy surface domains and
suppressing non-radiative recombination pathways. In a similar vein, the application of organometallic
compounds further exemplifies how targeted structural design can sustain this orderly growth trajectory.
Specifically, the introduction of 1-propanol-2-(1,2,3-triazol-4-yl) cobaltocenium hexafluorophosphate
(PTCoPF ) demonstrates a synergistic modulation of both kinetic control and comprehensive defect
6
passivation . The triazole ring within this organometallic salt coordinates strongly with undercoordinated
[58]
lead to mitigate deep-level defects, while its cobaltocenium cations and hexafluorophosphate anions work
concurrently to stabilize the overall lead-iodide framework and repair shallow-level vacancies. These robust
chemical interactions systematically retard the crystallization rate to ensure that the previously established
uniform nucleation landscape evolves naturally into steady grain coarsening. By sustaining this controlled