light absorption, [3,4] long diffusion length, [5] and low trapping densities. [6] The certified power conversion efficiency of perovskite solar cells has arrived at 22.1%. [7] Meanwhile, the newly developed photodetectors based on large size single-crystals also attained high performances. [8][9][10][11][12][13][14][15][16] So far, large-size singlecrystals have presented much longer charge carrier diffusion lengths and significantly lower trap-state densities, [5] but one of the key benefits of the thin-films is that it combines flexibility with the prospect of further improvements toward continuous, high throughput roll-to-roll (R-2-R) processing.The relative poor photophysical properties of perovskite thin-films are attributed to the inhibition of charge transport by the trap states due to random macroscopic alignment and crystal orientation that are rooted from poor crystal packing. For example, polycrystalline grains, which are always observed in spin-cast films, [17][18][19] exhibit large number of associated grain boundaries in which traps deteriorate quantum efficiency and photocarrier lifetime. [20] To narrow down the gap in photophysical property between the thin-films and single-crystals, it has become imperative to understand and to eventually achieve optimized crystal packing. Unfortunately, obtaining controlled packing through solution coating remains challenging, partly due to fast solvent evaporation, stochastic nucleation, and fluid flow instabilities. [21,22] There have been attempts to address above challenges. For example, 1D nanowires have been developed with fewer grain boundaries, traps, and longer photocarrier lifetime than their nanograin counterparts. [23][24][25] However, fabrication of uniformly coated large-area device appears to be challenging. [26] Bakr and co-workers developed a thermal-gradient-assisted directional crystallization to produce fully covered periodic microarrays with high crystal orientation and anisotropic charge transport properties. [27] However the thermal-gradient-assisted directional crystallization can be readily interrupted by airflow; and the crystal formation often takes hours to complete, making it unfavorable for high-throughput large-scale fabrication. Other approaches such as microgravure printing, slip-coating, and blade-coating were also reported to fabricate macroscopic aligned crystals, [16,26,28] however there were no information Solution coating of organohalide lead perovskites offers great potential for achieving low-cost manufacturing of large-area flexible optoelectronics. However, the rapid coating speed needed for industrial-scale production poses challenges to the control of crystal packing. Herein, this study reports using solution shearing to confine crystal nucleation and growth in large-area printed MAPbI 3 thin films. Near single-crystalline perovskite microarrays are demonstrated with a high degree of controlled macroscopic alignment and crystal orientation, which exhibit significant improvements in optical and optoelectronic propert...