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Palladium diselenide as a thus-far rarely studied group-10 transition metal dichalcogenide, has exhibited great potential in the field of optoelectronics due to their superior conductivity, high carrier mobility, and excellent stability. However, few works are reported on the application of low-dimensional PdSe2 in organic solar cells (OSCs). Herein, PdSe2 quantum dots (QDs) are introduced into the high-efficient nonfullerene OSCs for the first time by incorporating the solution-processable QDs in the hole transport layer (HTL) of the OSCs, leading to a dramatic efficiency enhancement of the devices. Upon PdSe2 QD addition, the maximum efficiency of the devices based on different active layer blends, including D18:Y6 and PM6:L8-BO, is improved to 18.12%, and 18.29%, with efficiency enhancement of 8.96% and 6.90%, respectively, compared with that of the reference devices. The effects of PdSe2 QDs on the optical absorption, photoluminescence spectrum of the hybrid HTL as well as the carrier mobility, electrochemical impedance spectroscopy, and transient photocurrent/transient photovoltage of the devices are deeply investigated, revealing the efficiency enhancement of the OSCs with PdSe2 QDs addition results from the improved conductivity, light scattering, and hole transport properties of the hybrid HTL embedded with PdSe2 QDs. [ABSTRACT FROM AUTHOR]

2D conjugated side-chain engineering is an effective strategy that is widely utilized to construct benzodithiophene-based polymers. Herein, an unconjugated side-chain strategy to design fused-benzodithiophene-based non-fullerene small molecule acceptors (SMAs) via vertical aromatic side-chain engineering on the ladder-type core is employed. Three SMAs named BTTIC-Th, BTTIC-TT, and BTTIC-Ph with thiophene, thieno[3,2-b]thiophene, and benzene, respectively, as side chains, are designed and synthesized. Three SMAs exhibit similar absorption ranges but different lowest unoccupied molecular orbital (LUMO) energy levels due to the different strength of the δ-inductive effect between vertical aromatic side chains and their electron-rich core. Organic solar cells based on PBDB-T:BTTIC-TT achieve a power conversion efficiency (PCE) of 13.44%, which is higher than the PCE of devices based on PBDB-T:BTTIC-Th (12.91%) and PBDB-T:BTTIC-Ph (9.14%). The difference in device performance is investigated by electrical and morphological characterizations. A large domain size and different types of π- π stacking are found in the bulk heterojunction layer of PBDB-T:BTTIC-Ph blend film, which are detrimental to exciton dissociation and charge transport. Overall, it is demonstrated that when designing unconjugated side chains, thieno[3,2-b]thiophene is superior to thiophene and benzene through its dual roles of promoting the LUMO energy level and optimizing the morphology. These results shed light on the side-chain engineering of high-performance non-fullerene SMAs. [ABSTRACT FROM AUTHOR]