Plasmonic nanostructures are successfully demonstrated in solar cells due to their broad spectra-selective resonance in the range of ultraviolet to near-infrared, and thus light absorption can be mostly improved and power conversion efficiency (PCE) further. Here, we demonstrate plasmonic dye-sensitized solar cells (DSSCs) using collapsible Au nanofingers to build photoanode to enhance light absorption. In this plasmonic DSSCs, by balancing local field enhancement due to gap-plasmon resonance and dye fluorescence quenching, the optimal gap size in collapsed Au/Al2O3/Au nanofingers is designed by twice the Al2O3 thickness and then deposited a TiO2 layer as photoanode. The results show that the PCE of DSSCs is mostly improved as compared to DSSCs with photoanode of Au/Al2O3/TiO2 films, which can be ascribed to the coupled local field enhancement within the sub-nanometer gaps. In addition, fluorescence of dyes on plasmonic nanofingers is nearly 10 times higher than plain Au/Al2O3/TiO2 films, which further proves the dye absorption enhancement. These plasmonic nanofingers enable the precise engineering of gap-plasmon modes and can be scaled up to wafer scale with low cost by the nanoimprint lithography technique, which suggests the feasibility of applying our result in constructing the photoanode for other types of solar cells.

All‐inorganic perovskites have recently drawn considerable attention due to their excellent optoelectronic properties. With the help of gap‐plasmon nanostructures, the optical properties of perovskites can be tuned through the coupled near‐field. Here, the optical coupling between CsPbBr3 quantum dots (QDs) and gap‐plasmon through placing QDs in a 2‐nm tetrahedral amorphous carbon gap region of collapsible Ag nanofingers is demonstrated. Compared to the CsPbBr3 QDs on SiO2, the photoluminescence (PL) of CsPbBr3 QDs on collapsed nanofinger is enhanced by 4 times and the lifetime decreases from 11.04 to 3.8 ns. A Purcell‐enhanced emission can be achieved by combining QDs and plasmonic nanofingers. In addition, the intensity of PL can be manipulated by the polarization of incident light because of the different polarization responses of dimer nanofingers. More importantly, PL intensity shows a quadric dependence on the incident power and lasing‐like PL spectra can be observed at room temperature by continuous‐wave laser excitation. Such observations can be ascribed to the strong coupling between CsPbBr3 QDs and surrounding Ag nanofingers. This finding indicates that it is possible to achieve lasing‐like PL through coupling CsPbBr3 QDs to the near‐field of plasmonic nanostructures, which can enrich the applications of CsPbBr3 QDs in nanolasing devices.