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Page 10 of 22 Song et al. Energy Mater. 2026, 6, 600019

electron-phonon coupling [129] . This enhances ionic mobility and can lead to increased non-radiative
recombination. At low temperatures (below -100 °C), carrier mobility is reduced due to localized states and
suppressed lattice motion , while at high temperatures (> 80 °C), thermal degradation and MA instability
[130]
+
become dominant concerns. FAPbI tends to undergo phase transitions from tetragonal (β phase, below
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~-140 °C), to hexagonal (-140 to ~30 °C), and then to cubic (α phase, above ~30 °C) [127] . Under
high-temperature conditions below ~150 °C and in the presence of moisture, FAPbI exhibits instability, with
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structural distortion involving transformation from the α phase to the non-perovskite δ phase, because the
FA cation size leads to dynamic fluctuations at intermediate temperatures [131,132] . At temperatures above
+
100 °C, phase decomposition and trap-assisted recombination further increase.

Consequently, the thermal cycling endurance of PSCs can be enhanced through interface engineering
between 2D and 3D perovskite layers, the introduction of self-healing compositions, and suppression of
phase transitions via compositional engineering of perovskite materials [133,134] . In addition, it has been
reported that the use of 2D capping layers and strain-relieving buffer layers prevents light-induced phase
segregation in mixed-halide perovskites under high-temperature conditions. These studies suggest promising
strategies for enhancing the thermal endurance of PSCs in space environments. On the other hand, to
prevent device degradation caused by extremely high and low temperatures, it is also essential to develop
thermally robust materials and to consider additional thermal management strategies, such as reflective
coatings, thermal straps, and heat-insulating films.

Low-light and partial illumination performance
In dark space environments encountered during deep-space exploration, eclipses, and on planetary surfaces
beyond direct sunlight, solar cells are required to operate under low-light conditions. Notably, PSCs can
perform efficiently at low irradiance while maintaining relatively high V and efficiency, owing to their
oc
superior electronic properties, such as low non-radiative recombination rates and high charge-carrier
mobility [135-137] . Corresponding to the characteristics of PSCs, Glowienka et al. investigated a
light-intensity-dependent analysis of current density-voltage (J-V) parameters to identify the mechanisms in
PSCs, such as bulk or interfacial recombination and series or shunt resistance [138] . Glowienka and
Raifuku et al. reported that PSCs exhibited superior performance by maintaining higher V value under
oc
0.1 mW cm illumination, compared to more severe V drop observed in c-Si solar cells, which exhibit a
-2
oc
higher ideality factor under low-light conditions [138,139] . Additionally, Guo et al. reported that
narrower-bandgap perovskites can efficiently harvest light at low irradiance [140] . These reports indicate that
PSCs can perform well in space environments with weak sunlight, even under shadowed conditions or
partial illumination of PV panels. Moreover, PSC modules may mitigate non-uniform power generation in
PV arrays through bypass diode integration and segmentation of the system into smaller cells [141,142] .

Radiation-induced performance enhancements
The response of perovskites to space radiation, including protons, electrons, γ-rays, and neutrons,
demonstrates their promising tolerance and unique self-healing characteristics. The intriguing and unique
recovery phenomenon about perovskite is that device performance can be temporarily improved under
certain radiation exposure. This has been attributed to radiation-induced defects passivating pre-existing
trap sites in the material. For example, some studies reported that PSCs exhibited a slight increase in fill
factor (FF) and efficiency immediately after exposure to a low, followed by a higher fluence of proton
irradiation (0.9 × 10 -3.8 × 10 cm ) [Figure 4D] . The proposed hypothesis is that ionizing radiation can
-2
[26]
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displace halide ions into vacancy sites and relieve lattice strain, effectively “healing” certain defects. In
particular, Lang et al. demonstrated the proton robustness of MAPbI by investigating the
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positive-intrinsic-negative (p-i-n) solar cells, resulting in stable V and FF at high proton energy of
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(~10 protons cm ) and slightly decreased short-circuit current density (J ) with optical degradation of
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-2
[23]
sc