A new electron-rich central building block, 5,5,12,12-tetrakis(4-hexylphenyl)-indacenobis-(dithieno[3,2-b:2',3'-d]pyrrol) (INP), and two derivative nonfullerene acceptors (INPIC and INPIC-4F) are designed and synthesized. The two molecules reveal broad (600-900 nm) and strong absorption due to the satisfactory electron-donating ability of INP. Compared with its counterpart INPIC, fluorinated nonfullerene acceptor INPIC-4F exhibits a stronger near-infrared absorption with a narrower optical bandgap of 1.39 eV, an improved crystallinity with higher electron mobility, and down-shifted highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels. Organic solar cells (OSCs) based on INPIC-4F exhibit a high power conversion efficiency (PCE) of 13.13% and a relatively low energy loss of 0.54 eV, which is among the highest efficiencies reported for binary OSCs in the literature. The results demonstrate the great potential of the new INP as an electron-donating building block for constructing high-performance nonfullerene acceptors for OSCs.

By integrating the advantages of the materials and two binary PSCs into one cell, a PCE of 13.73% is achieved in ternary PSCs.

Here, we combine two donor polymers with a relatively short synthesis method and fabricate ternary organic solar cells (OSCs) with a high efficiency and a decent figure-ofmerit. A series of characterizations show that the optimal morphology of the ternary blend is the result of the coupling and competition of PTQ10 and PTVT-T, where the molecular packing and phase separation motif of PTQ10 is broken but the strong aggregation of PTVT-T is suppressed, resulting in efficient charge transport and collection, as well as suppressed bimolecular recombination. Moreover, a previously reported solvent-vapor-assisted casting method, taken as an understanding-guided optimization, pushes the optimal system's efficiency to 19.11%. Furthermore, PTVT-T-containing systems clearly show better light soaking and thermal stability than the PTQ10 binary control system, benefiting from the durable polymer matrix. Our work provides a useful approach for developing efficient, stable, and low-cost OSCs based on state-of-theart donor/acceptor systems through morphology control of the ternary design.

In this work, sidechain engineering on conjugated fused-ring acceptors for conformation locking has been demonstrated as an effective molecular design strategy for high-performance nonfullerene organic solar cells (OSCs). A novel non-fullerene acceptor (ITC6-IC) was designed and developed by introducing long alkyl chains into the terminal electron-donating building blocks. ITC6-IC achieved definite conformation with a planar structure and better solubility in common organic solvents. The weak electron-donating hexyl incurs the upshift LUMO level of ITC6-IC, resulting in a higher V OC in comparison to the widely used ITIC. The OSCs based on PBDB-T:ITC6-IC revealed a promising PCE of 11.61 % and an expected high V OC of 0.97 V. The weaker π-π stacking induced by steric hindrance affords ITC6-IC with enhanced compatibility with polymer donors. The blend film treated with suitable thermal annealing exhibits a fibril crystallization feature with a good bicontinuous network morphology. Our results indicate the molecular design approach of ITC6-IC can be inspirational for future development of non-fullerene acceptors for high efficiency OSCs.In terms of high performance bulk heterojunction (BHJ) organic solar cells (OSCs), [1][2][3][4] various small-molecule acceptors (SMAs) have been explored as promising alternatives to the fullerene derivatives. [5][6][7][8][9][10][11][12][13][14] Non-fullerene SMAs have drawn increasing attention and developed rapidly in past

The morphology of organic solar cells (OSCs) is a core topic for reaching ultimate photovoltaic performance. Herein, we focused on the combination of two important morphology regulation strategies – ternary...