Over 15% Efficiency Polymer Solar Cells Enabled by Conformation Tuning of Newly Designed Asymmetric Small‐Molecule Acceptors

Abstract

The prosperous period of polymer solar cells (PSCs) has witnessed great progress in molecule design methods to promote power conversion efficiency (PCE). Designing asymmetric structures has been proved effective in tuning energy level and morphology, which has drawn strong attention from the PSC community. Two hepta-ring and octa-ring asymmetric small molecular acceptors (SMAs) (IDTP-4F and IDTTP-4F) with S-shape and C-shape confirmations are developed to study the relationship between conformation shapes and PSC efficiencies. The similarity of absorption and energy levels between two SMAs makes the conformation a single variable. Additionally, three wide-bandgap polymer donors (PM6, S1, and PM7) are chosen to prove the universality of the relationship between conformation and photovoltaic performance. Consequently, the champion PCE afforded by PM7: IDTP-4F is as high as 15.2% while that of PM7: IDTTP-4F is 13.8%. Moreover, the S-shape IDTP-4F performs obviously better than their IDTTP-4F counterparts in PSCs regardless of the polymer donors, which confirms that S-shape conformation performs better than the C-shape one. This work provides an insight into how conformations of asymmetric SMAs affect PCEs, specific functions of utilizing different polymer donors to finely tune the active-layer morphology and another possibility to reach an excellent PCE over 15%.

Ternary Organic Photovoltaic Cells Exhibiting 17.59% Efficiency with Two Compatible Y6 Derivations as Acceptor

“…It is known that charge mobility is closely related to molecular packing property of blend films. [ 46,47 ] The grazing‐incidence wide‐angle X‐ray scattering (GIWAXS) characterization was conducted to explore the influence of incorporating Y6‐1O content on molecular packing property of blend films, [ 15,16,48 ] as shown in Figure a. The corresponding out‐of‐plane (OOP) and in‐plane (IP) scattering profiles are shown in Figure 5b,c.…”

2D Side‐Chain Engineered Asymmetric Acceptors Enabling Over 14% Efficiency and 75% Fill Factor Stable Organic Solar Cells

“…The uniform surface morphologies in the blend films are favorable for the interface contacts at both ends of the active layers, facilitating charge transport and collection. [ 49 ] The AFM phase images show that PBDB‐T:IPT2F‐TT blend features more ordered fibrous phase separation morphology in comparison to two counterparts blends (Figure 4d–f). More homogenous and finer phase separation featuring a bicontinuous interpenetrating network is also observed for PBDB‐T:IPT2F‐TT blend from TEM images (shown in Figure S38, Supporting Information).…”

Enhancing the Photovoltaic Performance of Ladder‐Type Heteroheptacene‐based Nonfullerene Acceptors by Incorporating Halogen Atoms on Their Ending Groups

“…[ 2,7 ] It has been found that the introduction of fluorine atoms can reduce the optical bandgap of the resulting acceptor, accompanied by both enhancements in the absorption coefficient and the intermolecular interaction. [ 20,21 ] Thus, the photovoltaic properties of nonfullerene acceptors with fluorinated ending groups can be greatly improved. So far, most of the reported high‐performance acceptors, such as IEICO‐4F, IT‐4F, and Y6, contain fluorinated ending groups.…”