Currently, most tandem polymer solar cells (PSCs) suffer from poor device stability and drastic efficiency degradation, which originate from the use of acidic recombination layers (RLs) based on the well-known PEDOT:PSS (poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)). Our work describes a novel and efficient tandem architecture with an extended long-term stability. We introduce new pH-neutral material systems (i.e., self-doped conducting polymer and conjugated polyelectrolyte) that have not been incorporated as a RL in tandem solar cells previously, replacing PEDOT:PSS. In addition, we devise an innovative versatile composite system containing photoactive and interfacial materials into the tandem fabrication of an ideal self-organized recombination layer with outstanding features, including high optical transparency, low vertical resistance, and favorable ohmic contacts for each surface. These layers lead not only to performance enhancement through a perfect series connection for two sub-cells with no concomitant performance losses but also to structure simplification of the tandem devices via the self-assembly of the recombination layer. As a consequence, we demonstrate efficient and simplified tandem cells that are composed of five component layers without using PEDOT:PSS and exhibit a high power conversion efficiency of 10.2% with an extremely prolonged long-term stability compared with existing six-layered tandem cells using PEDOT:PSS.