Sequential deposition toward high efficiency semi-transparent binary all-polymer solar cells with over 5% light utilization efficiency

In semi-transparent organic solar cells (ST-OSCs), balancing the average visible transmittance (AVT) and power conversion efficiency (PCE) is crucial for achieving high light utilization efficiency (LUE). This work demonstrates a binary all-polymer ST-OSC with an LUE exceeding 5%, fabricated via sequential deposition. Further analysis reveals that this method adjusts its vertical phase distribution, thereby establishing a well-defined p-i-n structure during the layer-by-layer (LBL) process, which optimizes the morphology of the active layer. Benefiting from the superior morphology, the PBQx-TF/PY-IT-based LBL device achieved a high PCE of 19.01%, significantly outperforming the 17.69% PCE of its bulk heterojunction (BHJ) counterpart. The enhanced performance is attributed to efficient exciton generation, charge transport, and suppressed charge recombination, which collectively contribute to a high short-circuit current density and fill factor. Optical simulations confirm that the sequential deposition technique reduces energy dissipation within the active layer. Moreover, this approach yields semi-transparent all-polymer solar cells with LUE of 5.12%, setting a benchmark for all-polymer ST-OSCs.