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The development of perovskite solar cells (PSCs) has ushered in a new era of solar technology, characterized by its exceptional efficiency and cost-effective production. However, the soft and fragile nature of perovskites makes module encapsulation challenging. Polyolefin elastomers (POEs) have been reported to be promising encapsulants for perovskite modules. However, little research exists on identifying criteria among different types of POEs as encapsulants. Here, two POEs with different morphologies were compared as encapsulants. The first POE crystallizes during encapsulation (crystal content ∼40%), and the resulting shrinkage or warpage leads to delamination, causing minimodule failure. In contrast, perovskite minimodules encapsulated with a mostly amorphous POE exhibited better reliability and reproducibility. The best perovskite minimodules passed the thermal cycling test for 240 cycles between −40 and 85 °C and the damp heat test for 1419 h, according to the IEC 61215 standard. This study highlights the importance of the morphology of encapsulants in achieving high-quality encapsulation. Published by the American Physical Society2024 

Melt acidolysis polymerization of hydroquinone with a kinked monomer, biphenyl 3,4′-bibenzoate, afforded a novel liquid crystalline polymer (LCP), poly( p -phenylene 3,4′-bibenzoate) (poly(HQ-3,4′BB)). Selection of hydroquinone diacetate (HQ a ) or hydroquinone dipivilate (HQ p ) facilitated either a tan or white final polymer, respectively. 1 H NMR spectroscopy confirmed consistent polymer backbone structure for polymers synthesized with either derivative of hydroquinone. Poly(HQ-3,4′BB) exhibited the onset of weight loss at about 480 °C, similar to commercially available Vectra® LCP. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) revealed a glass transition temperature ( T g ) of 190 °C and an isotropic temperature ( T i ) near 330 °C. The observation of a melting temperature ( T m ) depended upon the thermal history of the polymer. Wide-angle X-ray scattering (WAXS) and polarized optical microscopy (POM) confirmed the formation of a nematic glass morphology after quench-cooling from the isotropic state. Subsequent annealing at 280 °C or mechanical deformation induced crystallization of the polymer. Rheological studies demonstrated similar shear thinning behavior for poly(HQ-3,4′BB) and Vectra® RD501 in the power law region at 340 °C. Zero-shear viscosity measurements indicated that HQ a afforded higher melt viscosities after identical polymerization conditions relative to HQ p , suggesting higher molecular weights.