Solution-processable small molecules for organic solar cells have attracted intense attention for their advantages of definite molecular structures compared with their polymer counterparts. However, the device efficiencies based on small molecules are still lower than those of polymers, especially for inverted devices, the highest efficiency of which is <9%. Here we report three novel solution-processable small molecules, which contain π-bridges with gradient-decreased electron density and end acceptors substituted with various fluorine atoms (0F, 1F and 2F, respectively). Fluorination leads to an optimal active layer morphology, including an enhanced domain purity, the formation of hierarchical domain size and a directional vertical phase gradation. The optimal morphology balances charge separation and transfer, and facilitates charge collection. As a consequence, fluorinated molecules exhibit excellent inverted device performance, and an average power conversion efficiency of 11.08% is achieved for a two-fluorine atom substituted molecule.

A ternary blend system with two donors and one acceptor provides an effective route to improve the performance of organic solar cells. A synergistic effect of polymer and small molecules is observed in ternary solar cells, and the power conversion efficiency (PCE) of the ternary system (8.40%) is higher than those of binary systems based on small molecules (7.48%) or polymers (6.85%).

Integrating metal-organic frameworks (MOFs) in microelectronics has disruptive potential because of the unique properties of these microporous crystalline materials. Nanoscale patterning is a fundamental step in the implementation of MOFs in miniaturised solid-state devices. Conventional MOF patterning methods suffer from a low resolution and poorly defined pattern edges. Here, we demonstrate for the first time resist-free, direct X-ray and e-beam lithography of MOFs. This process avoids etching damage and contamination, and leaves the porosity and crystallinity of the patterned MOFs intact. The resulting highquality patterns have a record sub-50 nm resolution, far beyond the state of the art in MOF patterning and approaching the mesopore regime. The excellent compatibility of X-ray and e-beam lithography with existing microfabrication processes, both in research and production facilities, provides an avenue to explore the integration of MOFs in microelectronics further. This approach is the first example of direct lithography of any type of microporous crystalline network solid, and marks an important milestone in the processing of such materials.

Large-scale fabrication of organic solar cells requires an active layer with high thickness tolerability and the use of environment-friendly solvents. Thick films with high-performance can be achieved via a ternary strategy studied herein. The ternary system consists of one polymer donor, one small molecule donor, and one fullerene acceptor. The small molecule enhances the crystallinity and face-on orientation of the active layer, leading to improved thickness tolerability compared with that of a polymer-fullerene binary system. An active layer with 270 nm thickness exhibits an average power conversion efficiency (PCE) of 10.78%, while the PCE is less than 8% with such thick film for binary system. Furthermore, large-area devices are successfully fabricated using polyethylene terephthalate (PET)/Silver gride or indium tin oxide (ITO)-based transparent flexible substrates. The product shows a high PCE of 8.28% with an area of 1.25 cm for a single cell and 5.18% for a 20 cm module. This study demonstrates that ternary organic solar cells exhibit great potential for large-scale fabrication and future applications.

Significant development has been achieved in nonfullerene organic solar cells. However, most of the high‐efficiency nonfullerene systems are composed of polymer donors and fused‐ring acceptors, and only a few small molecule donors can work well. Herein, a new A–D–A small molecule donor named NDTSR with naphtho[1,2‐b:5,6‐b′]dithiophene (NDT) as building blocks is synthesized. Two energy levels well‐matched fused‐ring acceptors ITIC and IDIC are chosen to construct all‐small‐molecule solar cells with NDTSR, respectively. When mixed with IDIC, a high power conversion efficiency (PCE) of 8.05% is achieved, which is the highest efficiency for NDT‐based small molecule donor. However, the NDTSR:ITIC system only exhibits a low PCE of 1.77%. The big difference in the performance of these two systems should be attributed to the different morphology and phase separation resulting from the crystallinity and aggregation ability of the acceptors. The results demonstrate that NDT‐based small molecule is a promising candidate donor for all‐small‐molecule systems, while the crystallinity of fused‐ring acceptors is a critical factor for optimizing the phase separation in the active layer.