Layer-by-layer (LbL) enables independent control of donor and acceptor layers in organic solar cells, yet the role of third components in shaping energetic disorder and carrier dynamics remains unclear. Here, we examine the layer-selective incorporation of IT-Th in LbL devices. Dual incorporation modifies vertical composition and molecular alignment, leading to a reorganized electronic state distribution near the band edges. This redistribution yields shallower tail states without relying solely on increased structural order. Time-resolved measurements show that prolonged carrier lifetimes arise from reduced electron–hole encounter probabilities caused by energetic decoupling, rather than suppressed recombination. These observations indicate that carrier lifetime does not directly reflect recombination losses and emphasize the role of tail-state regulation in LbL organic solar cells.