Fused Hexacyclic Nonfullerene Acceptor with Strong Near‐Infrared Absorption for Semitransparent Organic Solar Cells with 9.77% Efficiency

Abstract

A fused hexacyclic electron acceptor, IHIC, based on strong electron-donating group dithienocyclopentathieno[3,2-b]thiophene flanked by strong electron-withdrawing group 1,1-dicyanomethylene-3-indanone, is designed, synthesized, and applied in semitransparent organic solar cells (ST-OSCs). IHIC exhibits strong near-infrared absorption with extinction coefficients of up to 1.6 × 10 m cm , a narrow optical bandgap of 1.38 eV, and a high electron mobility of 2.4 × 10 cm V s . The ST-OSCs based on blends of a narrow-bandgap polymer donor PTB7-Th and narrow-bandgap IHIC acceptor exhibit a champion power conversion efficiency of 9.77% with an average visible transmittance of 36% and excellent device stability; this efficiency is much higher than any single-junction and tandem ST-OSCs reported in the literature.

An Alkylated Indacenodithieno[3,2‐b]thiophene‐Based Nonfullerene Acceptor with High Crystallinity Exhibiting Single Junction Solar Cell Efficiencies Greater than 13% with Low Voltage Losses

“…[10] Since then, many strategies have been applied to modify the structure of ITIC in order to adjust the absorption spectra and energy levels to further improve the PCE, for example, by changing the side chains, [17,18] extending the conjugation length, [19][20][21][22] and substituting the end acceptor groups. [13][14][15][16] To date, a few systems based on these NFAs have achieved a PCE of over 10%.…”

Dithieno[3,2‐b:2′,3′‐d]pyrrol Fused Nonfullerene Acceptors Enabling Over 13% Efficiency for Organic Solar Cells

“…[29][30][31][32][33][34][35][36][37] Based on the Shockley-Queisser efficiency limit model, the ideal bandgap (≈1.34 eV) of the photoactive layer for AM 1.5G illumination could achieve the optimal photovoltaic performance. [30,[39][40][41][42] Zhan and co-workers [43] and Jen and co-workers [44] have reported a fused-ring thiophenethieno [3,2-b]thiophene-thiophene-based hexacyclic low-bandgap NFA (named IHIC or 4TIC, 1.38 eV), exhibiting a PCE of 9.77% with an relative high visible transmittance. [30,[39][40][41][42] Zhan and co-workers [43] and Jen and co-workers [44] have reported a fused-ring thiophenethieno [3,2-b]thiophene-thiophene-based hexacyclic low-bandgap NFA (named IHIC or 4TIC, 1.38 eV), exhibiting a PCE of 9.77% with an relative high visible transmittance.…”

“…[38] Guided by this predictive principle, several methods have been developed to broaden the absorption spectra of NFAs, such as extending the conjugation and enhancing the ICT effect. [30,[39][40][41][42] Zhan and co-workers [43] and Jen and co-workers [44] have reported a fused-ring thiophenethieno[3,2-b]thiophene-thiophene-based hexacyclic low-bandgap NFA (named IHIC or 4TIC, 1.38 eV), exhibiting a PCE of 9.77% with an relative high visible transmittance. Hou and coworkers [45] have demonstrated an ultranarrow-bandgap NFA (IEICO-4F, 1.24 eV) through utilizing a spacer (alkoxy thiophene) to enhance the ICT effect and electron delocalization, indicating a PCE of 10.9% within a ternary OSC.…”

Environmentally-friendly solvent processed fullerene-free organic solar cells enabled by screening halogen-free solvent additives

“…Great efforts have been made to improve the power conversion effi-ciencies (PCEs) of OSCs by utilizing novel materials and new processing methods over the past decades [1,[20][21][22][23][24][25][26][27][28][29][30][31]. Recently, high-performance non-fullerene acceptor materials, especially the small-molecular acceptors (SMAs), were successfully developed [32][33][34][35][36][37][38][39][40][41][42][43][44][45]. These SMAs materials exhibit excellent solubility in non-halogen solvents, such as o-xylene (XY), anisole and tetrahydrofuran (THF) [46], which have brought the possibility of fabricating high-performance non-fullerene OSCs using non-halogen solvent systems.…”