A Mixed-Ligand Strategy to Modulate P3HT Regioregularity for High-Efficiency Solar Cells

Abstract

Sustainable synthesis of polythiophenes (e.g., P3HT) is highly desired for the development of low-cost organic solar cells. Regulating the regioregularity of P3HT is a promising way to boost its performance. Yet, few eco-friendly methods can prepare P3HT with tunable regioregularity. Herein, we put forward a facile strategy to finely modulate the regioregularity of P3HT from 90% to 98% by tuning the molar ratio of two ligands in direct arylation polycondensation. Moreover, the ligand effect on regioregularity is well elucidated with DFT calculations, and the regioregularity effect of P3HT in non-fullerene solar cells is clarified for the first time. Our calorimetric, microscopic, and scattering results show that regioregularity strongly impacts the polymer crystallinity and phase separation, and device performance of the blend films. The P3HT batch with a regioregularity of 95% yields an unprecedented power conversion efficiency of 10.82%. Importantly, this realization firmly provides optimism for cheap materials such as polythiophenes, which are made via eco-friendly polycondensation for the application of solar cells and beyond.

Brominated Polythiophene Reduces the Efficiency‐Stability‐Cost Gap of Organic and Quantum Dot Hybrid Solar Cells

“…[35] P3HT was made via direct arylation polycondensation according to the recent reports. [16][17][18] Additionally, P3HT-Br was prepared via postfunctionalization of P3HT according to the pioneering work by Li et al [53] All above reagents were from Energy Chemical.…”

“…The classical polythiophene, P3HT was synthesized according to our recent work via direct arylation polycondensation, which generally had reduced synthesis steps, high atom economy, and less toxic hazards. [16][17][18] As P3HT generally exhibits a shallow highest occupied molecular orbital energy level, it can't match well with PbS QDs, leading to high voltage loss and unfavorable carrier transport. [24,26] Therefore, it is highly desired to reduce the energy level of polythiophenes and flatten the energy landscape of QD/polymer heterojunction via a facile synthesis strategy.…”

“…Polythiophenes, one class of the facile‐processable and low‐cost photovoltaic materials, have drawn broad research interest in various solution‐processed photovoltaics, including organic solar cells (OSCs), [ 14–18 ] perovskite solar cells (PSCs) [ 19–23 ] and quantum dot solar cells (QDSCs). [ 24–26 ] For OSCs, polythiophenes have exhibited great competitiveness over high‐efficiency donors due to the markedly reduced synthesis steps and cost (two synthesis steps and 10 $ g −1 cost via eco‐friendly polycondensation).…”

“…[ 24–26 ] For OSCs, polythiophenes have exhibited great competitiveness over high‐efficiency donors due to the markedly reduced synthesis steps and cost (two synthesis steps and 10 $ g −1 cost via eco‐friendly polycondensation). [ 16,17 ] With the joint efforts, the photovoltaic performance based on simple polythiophenes and their functionalized derivatives have delivered the great breakthroughs, with power conversion efficiencies (PCEs) reaching ≈11% and over 17% respectively, [ 16,27,28 ] which further advance the progress of commercial applications of OSCs. [ 29–31 ] For PSCs, polythiophene materials have been applied as hole transport layers (HTLs), due to the favorable energy level alignment and hydrophobicity for high stability.…”

“…[5][6][7][8] To counter the challenges, more and more efforts have been devoted to developing high-performance and stable solar cells with low-cost photovoltaic materials, [9,10] considering the generally accepted golden triangle (efficiency, lifetime, and cost). [11][12][13] Polythiophenes, one class of the facileprocessable and low-cost photovoltaic materials, have drawn broad research interest in various solution-processed photovoltaics, including organic solar cells (OSCs), [14][15][16][17][18] perovskite solar cells (PSCs) [19][20][21][22][23] and quantum dot solar cells (QDSCs). [24][25][26] For OSCs, polythiophenes have exhibited great competitiveness over high-efficiency donors due to the markedly reduced synthesis steps and cost (two synthesis steps and 10 $ g −1 cost viaThe emerging solution-processed solar cells have attracted worldwide effort in the last decade.…”