The article reviews the recent advancements in organic solar cells (OSCs) based on non-fullerene (NF) acceptors, which have rapidly improved to achieve power conversion efficiencies (PCEs) exceeding 13%, surpassing the best fullerene-based OSCs. NF acceptors offer significant tunability in absorption spectra and electron energy levels, enabling new opportunities in device physics and photophysics. The review highlights the efficient charge separation in NF OSCs, characterized by high photocurrent and low voltage losses, and discusses the challenges and opportunities in material chemistry and device engineering. Key challenges include the anisotropic structures of NF acceptors, which require careful donor-acceptor pairing and morphological control. The review also explores the potential of tandem and ternary devices, semi-transparent OSCs, and the outlook for practical applications, emphasizing the need to reduce non-radiative recombination losses and improve stability.The article reviews the recent advancements in organic solar cells (OSCs) based on non-fullerene (NF) acceptors, which have rapidly improved to achieve power conversion efficiencies (PCEs) exceeding 13%, surpassing the best fullerene-based OSCs. NF acceptors offer significant tunability in absorption spectra and electron energy levels, enabling new opportunities in device physics and photophysics. The review highlights the efficient charge separation in NF OSCs, characterized by high photocurrent and low voltage losses, and discusses the challenges and opportunities in material chemistry and device engineering. Key challenges include the anisotropic structures of NF acceptors, which require careful donor-acceptor pairing and morphological control. The review also explores the potential of tandem and ternary devices, semi-transparent OSCs, and the outlook for practical applications, emphasizing the need to reduce non-radiative recombination losses and improve stability.