Thermally stable poly(3‐hexylthiophene): Nonfullerene solar cells with efficiency breaking 10%

Abstract

Solar cells featuring polythiophenes as donors are one of the optoelectronic devices that hold notable promises for commercial application, profiting from the lowest synthetic complexity and excellent scalability. However, the complex phase behaviors of polythiophenes and their blends put constraints on modulating electrical performance and thus realizing stable performance under thermal stress. In this contribution, we present a multi‐technique approach that combines calorimetry, scattering, spectroscopy, and microscopy to thoroughly probe the thermodynamic mixing, thermal properties of materials, the evolution of nanoscale domain structure, and device performance of poly(3‐hexylthiophene) (P3HT) with a range of nonfullerene acceptors (NFAs) such as ITIC, IDTBR, and ZY‐4Cl. Accordingly, two blending guidelines are established for matching these popular NFAs with P3HT to enable highly efficient and thermally stable cells. First, blend systems with weak vitrification and hypo‐miscibility are excellent candidates for efficient solar cells. Furthermore, high thermal stability can be achieved by selecting NFAs with diffusion‐limited crystallization. The P3HT:ZY‐4Cl blend was found to endow the best performance of over 10% efficiency and an exceptionally high T80 lifetime of >6000 h under continuous thermal annealing, which are among the highest values for P3HT‐based solar cells. This realization of high thermal stability and efficiency demonstrates the remarkable potentials of simple polythiophene :nonfullerene pairs in electronic applications.

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

“…With this challenge in mind, we further examined the thermal stability of the developed hybrid QD/polythiophene solar cells under 85 °C thermal aging in inert condition according to our prior reports. [ 14,15 ] Encouragingly, hybrid QD/polythiophene solar cells presented a striking upward trend after 2 h thermal annealing, especially for P3HT‐Br‐based devices ( Figure 7 a). The promising performance enhancement under thermal stress was similar to the phenomenon that PbS QD solar cells witnessed the significant performance improvement after the storage in dry air.…”

“…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).…”

“…[41][42][43] Despite the benefits, most hybrid QD and polythiophene solar cells can only achieve the inferior photovoltaic performance below 8%, [24,26,32] which lagged far behind the champion performance of that with the high-cost and complex organic photovoltaic materials, e.g., diketopyrrolopyrrole-based polymer, [39] poly[(2,6-(4,8-bis(5-(2ethylhexyl-3-fluoro)thiophen-2-yl)-benzo][1,2-b:4,5-b0] dithiophene))-alt-(5,5-(10,30-di-2-thienyl-50,70-bis (2-ethylhexyl) benzo [10,20-c:40,50-c0]dithiophene-4,8-dione) (PM6) [44,45] and the random polymer (asy-ranPBTBDT) [46] (12%-14%). Additionally, the stability investigations of hybrid QD and organic solar cells, especially for thermal stability according to IEC 61 215 standards, fall far behind those of the PSC and OSC counterparts, [15,18] which markedly compromises the competitiveness in a commercial application. Therefore, it is highly deserved to develop facile strategies to further enhance the performance and stability of low-cost hybrid QD and polythiophene solar cells and uncover the detailed relationships between material properties and device performance, thus offering favorable guides for efficient and stable hybrid solar cells.…”

“…[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.…”

Regioisomeric Polymer Semiconductors Based on Cyano-Functionalized Dialkoxybithiophenes: Structure–Property Relationship and Photovoltaic Performance

“…The HH coupling typically results in a highly twisted molecular backbone due to the accompanying large steric hindrance, thereby reducing the effective π-conjugation and crystallinity of the resulting polymer. Poly(3-alkylthiophene) containing a small amount of HH linkage exhibited obviously inferior device performance in both OFETs and PSCs [21][22][23]. In contrast, the HT coupling yielded a higher polymer film crystallinity with a planar backbone conformation and achieved improved optoelectronic properties, as exemplified by the regioregular HT-linked poly(3-hexylthiophene) (rr-P3HT) [2,24,25].…”