摘要： Heterojunctions formed by two-dimensional (2D) layered semiconducting materials have been studied extensively in the past several years. These van der Waals (vdW) structures have shown great potential in future electronic and optoelectronic devices. However, the optoelectronic performance of these devices is limited by the indirect band gap of the multilayer materials and low light absorption of single layer materials. Here, we fabricate photodetectors based on heterojunctions composed of n-type multilayer α-Indium Selenide (In2Se3) and p-type Tungsten Diselenide (WSe2) for the first time. The direct band gap of multilayer α-In2Se3 and type-II band alignment of the WSe2/In2Se3 heterojunction enable high optoelectronic performance of the devices at room temperature in the air. Without light illumination, the dark current is effectively suppressed to 10-13 A under -1 V bias and a high rectification ratio of 7.37×103 is observed. Upon laser illumination with the wavelength of 650 nm, the typical heterojunction device exhibits a photocurrent on/off ratio exceeding 1.24×105, a maximum photo responsivity of 26 mA/W and short photoresponse time of 2.22 ms. Moreover, the heterojunction photodetectors show obvious light response in the wavelength range from 650 nm to 900 nm. The present 2D vdW heterojunctions composed of direct band gap multilayer materials show great potential in future optoelectronic devices.