Temperature-Regulated Growth of Thickness-Modulated Bi2O2Se Lateral Homojunctions for Self-Powered Broadband Photodetection.

Two-dimensional lateral homojunctions can introduce built-in electric fields without dissimilar-material interfaces, but their direct construction remains challenging. Here, we report a temperature-regulated vapor-phase growth strategy for constructing thickness-modulated Bi2O2Se lateral homojunctions. By combining low-temperature lateral growth with rapid heating-induced local thickening, laterally continuous thin-thick regions are formed within individual Bi2O2Se flakes. The thickness-dependent band structure is expected to induce a band offset at the lateral interface, thereby generating a built-in electric field for carrier separation and zero-bias photodetection. The resulting self-powered photodetector exhibits a broadband response from 350 to 1050 nm, with a responsivity of 0.41 A/W, a detectivity of 2.48 × 1011 Jones, response/recovery times of 9.4/5.6 ms, and good linear power dependence. Moreover, single-pixel imaging demonstrates its potential for spatial optical sensing and self-powered imaging. This work provides a simple temperature-regulated route for engineering Bi2O2Se lateral homojunctions and highlights their promise for low-power broadband optoelectronics.