Highly thermally stable all-polymer solar cells enabled by photo-crosslinkable bromine-functionalized polymer donors. (1st May 2020)

• Record Type: Journal Article
• Authors: Lin, Zhenkun; Zhang, Li; Tu, Silong; Wang, Wen; Ling, Qidan
• Is Part Of: Solar energy. Volume 201(2020)
• Page Start: 489
• Page End: 498
• Publication Date: 2020-05-01
• Subjects: Photo-crosslinkable -- Bromine-functionalized -- Thermal stability -- All-polymer solar cells; Solar energy -- Periodicals; Solar engines -- Periodicals; 621.47
• DOI: 10.1016/j.solener.2020.03.035
• Languages: English
• ISSNs: 0038-092X

Abstract

Graphical abstract: Highlight: Novel photo-crosslinkable polymers PBDT(T)FTAZ-Bx have been successfully obtained. Incorporation of proper Br-units into PBDT(T)FTAZ can boost stability and efficiency. Photo-crosslinked devices afforded excellent thermal stability with high efficiency. Abstract: Here, high performance polymers bearing photo-crosslinkable function are developed for all-PSCs to achieve both high efficiency and stability. Then, a series of novel -(D-A)a -(D-D1 )b -type photo-crosslinkable bromine (Br)-functionalized polymer donors PBDT(T)FTAZ-BX were synthesized, in which typical benzodithiophene (BDT) derivative was as first component (D), thiophene-difluro-benzotriazole (FTAZ) derivative was as second component (A), new simple BDT-based functionality appended Br-unit synthesized in this study was as third component (D1 ). The effects of Br-functionalized component on the photoelectric properties of the polymers were investigated. Moreover, UV-mediated photo-crosslinking effects on performance and thermal stability were thoroughly explored. All-PSCs based on these photo-crosslinkable polymers and N2200, but without photo-crosslinking, displayed a highest PCE of 7.21%, which was achieved by an optimized PBDT(T)FTAZ-B5 -based device. As results, photo-crosslinked PBDT(T)FTAZ-B5 + UV5min-based devices afford extraordinarily excellent thermal stability, in which high retention rate of 91.8% of the maximum PCEavg and the intrinsic performance (PCEmax : 6.12%) are maintained even after 72 h 150 °C annealing. For comparison, reference PBDT(T)FTAZ-based devices only display PCEmax value of 5.13% and retain 84.2% of their maximum PCEavg under same aging. This contrasting result indicates that developing photo-crosslinkable Br-functionalized polymers is an effective strategy to further advance in both stability and efficiency of all-PSCs.