[21p-B202-1~13] 13.9 化合物太陽電池

▼ [21p-B202-3] Improved Photovoltaic Properties of Few-layer WS_0.3Se_1.7/WO_x Lateral p⁺-n Junctions

〇(D)Abdul A Kuddus¹、Kojun Yokoyama¹、Keiji Ueno¹、Hajime Shirai¹ (1.Saitama University)

キーワード：2D WS2-xSex, Lateral p+-n junction, Solar cell

We investigated the photovoltaic properties of the lateral p⁺-n junction composed of few-layers WS_0.3Se_1.7 including chalcogenide vacancies generated by the atmospheric-pressure plasma followed by laser irradiations via field-effect transistor structures. The lateral p⁺-n junction was formed on the few-layer WS_0.3Se_1.7 by the He/O₂ plasma followed by the laser irradiations with different excitation wavelengths using a shadow metal mask. A laser irradiation of 420 nm promoted the generation of sulfur vacancies of WS_0.3Se_1.7 layers and the improved rectification behavior of current-voltage characteristics in the lateral p⁺-n junction. They also show a photovoltaic effect with a short-circuit current (I_SC) of order of 10^-9 A and an open-circuit voltage of 0.788 V. Further increase of I_SC of an order of 10^-6 A was obtained by inserting a silver mirror layer between the dielectric layer of Al_0.73Ti_0.26O_y (ATO) and the c-Si substrate which originate from the enhanced multiple reflection in the Fabry-Perot cavity. Ammonium tetrathiotungstate (NH₄)₂WS₄ and mixture of N-metyl-2-Pyrrolidone (NMP) (55 wt.%), methylamine (30 wt.%), and 2-aminoethanol (15 wt.%) were used as a precursor and solvent. The WS_x few-layers with a thickness of 3-5 nm were fabricated by spin-coat at 500 rpm for 10 s followed by 4000 rpm for 60 s on thermally grown (th-) SiO₂ (285 nm) and mist CVD grown ATO (50-100 nm) coated c-Si substrates. Subsequently, the selenization of WS_x was executed at T_f of 600 °C for 20 minutes.