Two-dimensional　p-type/intrinsic/n-type　(p-i-n)　homojunction　opens　up　exciting　opportunities　for　the　advancement　of　next-generation　electronic　and　optoelectronic　devices.　However,　it　is　urgent　to　explore　superior　two-dimensional　materials　for　p-i-n　homojunction　to　enhance　optoelectronic　performance.　Herein,　the　electronic　structures,　optical　properties　of　monolayer　XYN3　(X=V,　Nb,　Ta;　Y=Si,　Ge),　and　the　related　p-i-n　homojunctions　are　constructed　and　investigated　systematically　based　on　the　framework　of　density　function　theory　and　non-equilibrium　Green＇s　function　calculations.　The　electronic　structures　and　optical　absorption　of　these　stable　monolayers　reveal　that　they　show　semiconductor　characteristic　with　indirect　bandgaps　of　1.23∼2.13　eV,　which　possess　strong　absorption　of　visible　light.　The　simulations　of　the　p-i-n　homojunctions　based　on　these　monolayers　highlight　that　VSiN3　and　TaSiN3-based　p-i-n　junctions　possess　maximum　photocurrent　densities　of　21.43　and　18.48　A/m2,　respectively.　Moreover,　the　photoresponses　of　VSiN3　and　TaSiN3-based　p-i-n　junctions　can　reach　up　to　0.61　and　0.55　A/W,　respectively,　demonstrating　that　VSiN3　and　TaSiN3-based　p-i-n　junctions　could　be　the　ideal　candidates　for　optoelectronic　devices.　Our　work　is　expected　to　pave　the　way　for　the　realization　of　2D　p-i-n　homojunction　optoelectronic　devices.　©　2024　Elsevier　B.V.