Vertical-Phase-Locking Effect in Efficient and Stable All-Polymer-Hosted Solar Cells

All-polymer solar cells with bulk-heterojunction films composed of polymeric donors and acceptors are distinguished for their outstanding device stability. However, unfavorable thermodynamic mixing of polymers induced severe phase-separated morphology related to electron–phonon coupling, limiting the practical development of high-efficiency organic solar cells (OSCs). Herein, we obtain an enhanced power conversion efficiency in all-polymer-hosted OSCs prepared by a guest–nanofill strategy, where a third component (small molecule guest, B1) is employed to manipulate the electron–phonon interactions associated with the diffusion-mediated excitons dissociation and charge transport properties of the binary film. Encouragingly, the guest-nanofilled OSCs exhibit notably enhanced thermal stability, as the nanofiller B1 molecules allow the vertical distribution of the donor: acceptor to exhibit a locked pattern during the aging process, which can be figuratively termed as “vertical-phase-locking effect”. The guest–nanofill strategy in this work provides a unique approach toward the development of high-performance all-polymer electronics.