Future lightweight, flexible, and wearable electronics will employ visible‐light‐communication schemes to interact within indoor environments. Organic photodiodes are particularly well suited for such technologies as they enable chemically tailored optoelectronic performance and fabrication by printing techniques on thin and flexible substrates. However, previous methods have failed to address versatile functionality regarding wavelength selectivity without increasing fabrication complexity. This work introduces a general solution for printing wavelength‐selective bulk‐heterojunction photodetectors through engineering of the ink formulation. Nonfullerene acceptors are incorporated in a transparent polymer donor matrix to narrow and tune the response in the visible range without optical filters or light‐management techniques. This approach effectively decouples the optical response from the viscoelastic ink properties, simplifying process development. A thorough morphological and spectroscopic investigation finds excellent charge‐carrier dynamics enabling state‐of‐the‐art responsivities >102 mA W−1 and cutoff frequencies >1.5 MHz. Finally, the color selectivity and high performance are demonstrated in a filterless visible‐light‐communication system capable of demultiplexing intermixed optical signals.

Analytical electron microscopy reveals local molecular arrangements of PBDB-T:ITIC determining performance of current organic solar cells.

Inkjet printing (IJP) of polymer solar cells is ideal for small‐area off‐grid electronics with low power consumption. However, IJP is quite a complex technique compared with techniques such as spin coating or doctor blading. The IJP of polymer blends is reported based on ITIC derivatives as non‐fullerene acceptors (NFAs) using non‐halogenated solvents. The results show that fluorination of NFA is essential to form highly stable inks in o‐xylene, because ITIC has significantly insufficient solubility compared with ITIC‐4F. The importance of tetralin as a multifunctional co‐solvent for printing highly efficient PM6:ITIC‐4F blends is demonstrated, as even at very low concentrations, tetralin not only improves ink jettability and open nozzle time, but also improves drying behavior of the blend layer, resulting in blends with homogeneous micro‐ and nanoscale morphology. The resulting solar cells using inkjet‐printed polymer blends show a maximum efficiency of 10.1%. Moreover, IJP produces significant changes in the nanoscale and microscale morphology. In particular, the formation of a thin PM6 capping layer on the blend surface along with improved phase separation and crystallinity in both the donor and acceptor greatly reduces the recombination of charge carriers in thick blends, making inkjet‐printed photoactive films very promising for industrial applications.