Abstract
The poor electron transport ability of the polymer acceptor is one of the factors restricting the performance of all-polymer solar cells. The percolation network of conjugated polymers can promote its charge transfer. Hence, we aim to find out the critical molecular weight (MW) of N2200 on the forming of the percolation network and to improve its charge mobility and thus photovoltaic performance of J51:N2200 blend. Detailed measurements demonstrate that when the MW of N2200 is larger than 96k, a percolation network structure is formed due to the chain tangled and multi-chain aggregations. Analysis of kinetic experiments reveals that it is the memory of the N2200 long chain conformation and the extent of aggregation in solution are carried into cast films for the formation of the percolation network. Thus, the electron mobility increases from 5.58 × 10−6 cm2V−1s−1 (N220017k) to 9.03 × 10−5 cm2V−1s−1 when the MW of N2200 is >96k. It led to a balance between hole and electron mobility. The μh/μe decrease from 16.9 to 1.53, causing a significant enhancement in the PCEs, from 5.87 to 8.28% without additives.
Highlights
All-polymer solar cells have attracted widespread attention due to their unique advantages, such as good morphological stability and outstanding mechanical properties (Zhou et al, 2014; Kim et al, 2015; Zhang et al, 2018; Xu et al, 2019; Yang et al, 2019a,b; Zheng et al, 2019)
Through a detailed study of the intrinsic feature of the N2200, we revealed the mechanism behind the N2200 percolation network structure
The intensity of J51 at 637 nm increased with the increase of N2200 molecular weight (MW). This means that the phase purity of J51 in the blend system is strengthened as the MW of N2200 increases. These results indicate that the N2200110k is long enough to form a percolation network structure compared to other MWs
Summary
All-polymer solar cells (all-PSCs) have attracted widespread attention due to their unique advantages, such as good morphological stability and outstanding mechanical properties (Zhou et al, 2014; Kim et al, 2015; Zhang et al, 2018; Xu et al, 2019; Yang et al, 2019a,b; Zheng et al, 2019). Their efficient uses still cannot compete with the polymer–small molecules system (Zhu et al, 2019; Liu et al, 2020).
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
