Supersaturation-engineered wafer-scale growth of anisotropic 2D organic crystals for uniform polarimetric sensing

Organic single crystals endowed with intrinsic anisotropy hold great promise for the realization of miniaturized, polarization-sensitive photodetectors. However, conventional dip-coating approaches struggle to produce wafer-scale single-crystalline films, as the supersaturation conditions optimized for nucleation invariably conflict with those required for crystal growth, leading to fragmented domains and compromised device performance. Here, we introduce an in situ seeded dip coating (SDC) strategy that overcomes this limitation by engineering supersaturation to temporally decouple nucleation from crystal growth. This enables the scalable production of ultrathin two-dimensional molecular crystal (2DMC) films with exceptional uniformity across wafer dimensions. Organic field-effect transistor arrays fabricated from these 2DMCs exhibit high average charge carrier mobility (14.5 cm² V^-1 s^-1) and spatial homogeneity, evidenced by an ultralow mobility coefficient of variation (CV) of 4.5%. These arrays demonstrate robust polarization sensitivity with an average dichroic ratio (DR) of 2.2 and a low DR CV of 8.6%. Capitalizing on this uniformity, we constructed dual-device pixel units capable of full-range 180° polarization angle identification, enabling direct application in polarization-encoded optical encryption. The SDC technique provides a scalable pathway for practical high-performance organic polarization-sensitive optoelectronics.