Exploiting Noncovalently Conformational Locking as a Design Strategy for High Performance Fused-Ring Electron Acceptor Used in Polymer Solar Cells

Abstract

We have developed a kind of novel fused-ring small molecular acceptor, whose planar conformation can be locked by intramolecular noncovalent interaction. The formation of planar supramolecular fused-ring structure by conformation locking can effectively broaden its absorption spectrum, enhance the electron mobility, and reduce the nonradiative energy loss. Polymer solar cells (PSCs) based on this acceptor afforded a power conversion efficiency (PCE) of 9.6%. In contrast, PSCs based on similar acceptor, which cannot form a flat conformation, only gave a PCE of 2.3%. Such design strategy, which can make the synthesis of small molecular acceptor much easier, will be promising in developing a new acceptor for high efficiency polymer solar cells.

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

“…Among the highest performing NFAs, linear rod-like acceptor-donor-acceptor (A-D-A) structures incorporating fused ladder-type aromatics have attracted much interest. Common donor units include 4,9-dihydro-s-indaceno[1,2-b:5,6-b′]dithiophene (IDT) [5][6][7][8][9] and 6,12-dihydro-dithienoindeno [10][11][12][13][14][15][16][17][18] In both cases, the fused core facilitates π-electron delocalization and improves the π-π stacking between molecules, hence enhancing the intrinsic charge carrier mobility.In 2015, Zhan and coworkers reported a new NFA, 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11--b′]dithiophene (ITIC) (Scheme 1), which is comprised an electron-donating IDTT-based core flanked by two electron-withdrawing units of 1,1-dicyanomethylene-3-indanone (IC), that exhibited a promising PCE of 6.8% at that time. [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.…”

“…Among the highest performing NFAs, linear rod-like acceptor-donor-acceptor (A-D-A) structures incorporating fused ladder-type aromatics have attracted much interest. Common donor units include 4,9-dihydro-s-indaceno[1,2-b:5,6-b′]dithiophene (IDT) [5][6][7][8][9] and 6,12-dihydro-dithienoindeno [10][11][12][13][14][15][16][17][18] In both cases, the fused core facilitates π-electron delocalization and improves the π-π stacking between molecules, hence enhancing the intrinsic charge carrier mobility.…”

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.…”

Enhanced power conversion efficiency in iridium complex-based terpolymers for polymer solar cells

“…1,2 Very recently, BHJ OSCs with high power conversion efficiencies (PCE) exceeding 9% have been broadly demonstrated. [3][4][5][6][7][8][9] To improve the PCEs of OSCs, numerous strategies have been employed through materials innovation and device engineering. (i) The first and most important is to design and synthesize new suitable donor-acceptor (D-A) type conjugated oligomers or alternating copolymers with high optical absorption, low bandgap, relatively lower highest occupied molecular orbital (HOMO) energy levels and high hole mobility in order to function as good electron donors in BHJ OSCs.…”