Abstract2D transition metal dichalcogenides (TMDs) are promising candidates for realizing ultrathin and high‐performance photovoltaic devices. However, the external quantum efficiency (EQE) and power conversion efficiency (PCE) of most 2D photovoltaic devices face great challenges in exceeding 50% and 3%, respectively, due to the low efficiency of photocarrier separation and collection. Here, this study demonstrates photovoltaic devices with defect‐free interface and recombination‐free channel based on 2D WS2, showing high EQE of 92% approaching the theoretical limit and high PCE of 5.0%. The high performances are attributed to the van der Waals metal contact without interface defects and Fermi‐level pinning, and the fully depleted channel without photocarrier recombination, leading to intrinsic photocarrier separation and collection with high efficiency. Furthermore, this study demonstrates that the strategy can be extended to other TMDs such as MoSe2 and WSe2 with EQE of 92% and 94%, respectively. This work proposes a universal strategy for building high‐performance 2D photovoltaic devices. The nearly ideal EQE provides great potential for PCE approaching the Shockley–Queisser limit.

Owing to their unique characteristic of direct mechanical‐to‐optical energy conversion, mechanoluminescence (ML) crystals have drawn considerable interest for visible stress sensing, flexible and stretchable displays, and advanced anti‐counterfeiting. However, among the visible emissions of synthetic ML materials, high‐performance red‐emission semiconductors with ideal color‐rendering indices are relatively scarce, which restricts their future applications. In this work, red ML emission with CIE coordinates (0.6395 and 0.3572) in Mn‐doped ZnGa2S4 prepared by a molten salt shielding synthesis method in the air is reported. ZnGa2S4 has a cubic crystal structure composed of a layered [ZnS4] tetrahedral unit that plays an important role in efficient ML. Based on density functional theory calculations, the relationship between ML performance and crystal structure is revealed, which will help in the development of new high‐quality ML materials. The Mn‐doping of ZnGa2S4 causes a slight deformation of the crystal structure, leading to band bending and the formation of ML features in response to mechanical stimuli. The deep‐red ML emission of the ZnGa2S4:Mn crystals prepared by this method holds great promise for advanced flexible and stable displays and force/pressure sensor applications.

Electrides are a class of materials in which electrons are not bound to atoms but are similar to anions in crystals. Up to now, there are more than 300 electrides...