Molecular　semiconductors　(MSCs)　are　known　as　ideal　candidates　for　constructing　room-temperature　spin-charge　interactive　devices　due　to　their　long　spin　lifetimes　and　abundant　photoelectric　properties.　These　devices　can　achieve　novel　and　valuable　functionalities　such　as　room-temperature　supply　units　of　fully　spin-polarized　current.　Unfortunately,　their　performances　(sub-0.1 nA)　remain　unsatisfactory　due　to　limited　charge　and　spin　injection　efficiency,　which　can　hardly　be　improved　despite　great　efforts　thus　far.　Herein,　from　the　theoretical　side,　an　interfacial　tunnel　layer　with　precisely-controlled　barrier　in　spintronic　devices　may　simultaneously　enhance　spin　and　charge　injection.　Accordingly,　a　solution-processed　small　molecule　with　smooth　morphology　and　amorphous　structure　is　introduced　to　form　a　uniform　and　well-controllable　barrier　in　molecular　spin-photovoltaic　devices.　By　modulating　the　thickness　to　effectively　control　the　barrier,　both　spin　and　charge　injection　efficiency　increase　by　＞　150%.　Thus,　the　spin-charge　interactive　functionalities　as　supply　units　of　fully　spin-polarized　current　have　also　been　significantly　improved　than　the　current　record　at　room　temperature,　the　output　fully　spin-polarized　current　(＞2 nA)　is　1200%-larger,　and　the　output　power　increases　by　＞　50　times.　Moreover,　the　interface-modified　spintronic　devices　exhibit　excellent　stability　even　after　70　days　of　exposure　to　air,　which　is　essential　for　practical　applications　in　the　future.　©　2024　Wiley-VCH　GmbH.