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

Abstract

have aroused worldwide research efforts to fulfill the carbon-neutrality target in near future. [1,2] The burgeoning solutionprocessed solar cells hold great promise for the drop of global temperature to reach the net-zero scenario by 2050. [3,4] Despite the great advance of organic and hybrid solar cells in the past decade, their commercial applications still suffer from great resistance, compared with the welldeveloped c-silicon photovoltaics. [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. Developing efficient, stable, and cost-effective solar cells is strongly desirable in countering the growing global warming. Nevertheless, the photovoltaic performance and stability of hybrid solar cells based on lowcost polythiophenes are far from satisfactory, due to their high-lying energy levels and excessive aggregation. Herein, it is shown that brominated polythiophene (P3HT-Br), prepared via a facile two-step approach can effectively facilitate charge transport and suppress recombination in quantum dot (QD)/ organic heterojunctions. Accordingly, the power conversion efficiency of the optimized hybrid polythiophene/QD cell is boosted from 8.7% to 11% (a 26% increase) with markedly reduced energy loss. More strikingly, the device achieves record-high thermal stability with a lifetime of over 400 h maintaining 80% of the initial performance. Both device efficiency and stability are the best reported for polythiophene/QD hybrid solar cells. Moving forward, brominated polythiophenes hold great application in perovskite solar cells with significantly improved performance and offer new opportunities for other emerging solar cells.

Processing Poly(3‐Hexylthiophene) Interlayer with Nonhalogenated Solvents for High‐Performance and Low‐Cost Quantum Dot Solar Cells

“…With these benefits, we prepared the directly synthesized QDs according to our recent work. [21,22] The nuclear magnetic resonance spectrum of P3HT can be found in Figure S1, Supporting Information, from which we can determine the regioregularity (%90%). Gel permeation chromatography was employed to characterize the molecular weight and polydispersity index of P3HT, and the results are plotted in Figure S2 and Table S1, Supporting Information.…”

“…[17,35] Nevertheless, the open-circuit voltage (V oc ) and FF still had great improvement room, according to our recent work. [21] We proceeded to investigate the performance of QD solar cells with P3HT processed by o-XY and observed the marked improvement of V oc , J sc , and FF (Figure 1b and Table 1), resulting in a champion PCE of 8.7% (Figure S9, Supporting Information). More strikingly, the achieved V oc of 0.62 V was the record voltage value reported to date for QD/P3HT hybrid solar cells.…”

“…The root-mean-square surface roughness (R q ) of all polythiophene films was extracted, and the films with CF and THF presented the high R q of %1.5 nm, which was not favorable for carrier transport between QDs and P3HT, as revealed by our recent work. [21,22] For the P3HT film processed with o-XY, the moderate R q for efficient carrier transport was achieved, which resulted in the improved photovoltaic performance. Additionally, we further performed the fast Fourier transform analysis of power spectral density (PSD) profiles, which can deliver a quantitative analysis of feature sizes (Figure 2b).…”

Ternary organic solar cells featuring polythiophene

“…Thus, constructing ternary blends might be an efficient means to obtain over 10% efficiency in this kind of solar cell. Moreover, the cells might be mechanically stretchable due to the entanglement of PT and polymer acceptors [2,[116][117][118] . In addition, combining ternary blends with flexible substrates, such as flexible conductive textiles, is an effective strategy for achieving wearable electronic devices.…”

Performance Enhancement of Crystal Silicon Solar Cell by a CsPbBr3–Cs4PbBr6 Perovskite Quantum Dot @ZnO/Ethylene Vinyl Acetate Copolymer Downshifting Composite Film

“…They are widely used in light-emitting devices, displays, and photovoltaic devices for their excellent optical and electrical performance. [30][31][32][33][34][35][36][37][38][39] Their enhanced designability, remarkable sensitivity to the UV-blue photons, and high photoluminescence quantum yields (PLQYs) of 90% make perovskite QDs potential candidates for downshifting materials in CSSCs. [40][41][42][43] Many strategies have been reported to continuously improve the performance of perovskite QDs, including doping engineering, surface ligand modification, and coating strategies.…”