Combinative Effect of Additive and Thermal Annealing Processes Delivers High Efficiency All-Polymer Solar Cells

Abstract

The combinative effects of thermal annealing and additive processes on the performance of all-polymer bulk heterojunction (BHJ) solar cells with composites of different donor polymers (PTQ1, P3HT, PTB7-Th) and poly[1,8bis(dicarboximide)-2,6-diyl]-alt-5,5′-(2,2′-bithiophene)P(NDI2OD-T2) [PolyeraActivInk N2200] were investigated. We found that devices treated with both processes show significant improved performance compared with those treated with either process alone. To reveal the mechanism of this enhancement in device performance, the optical and electrical properties of all-polymer blends were carefully investigated in the PTQ1/N2200 system. The synergetic effect of both processes can largely enhance the polymer aggregation, especially for N2200, leading to improved absorbance, improved charge mobility, and thus higher device performance. In addition, the device efficiency can be further enhanced by postannealing which can improve the interface between the active layer and Al cathode, as revealed by atomic force microscopy investigations. Moreover, the approaches reported here provide a simple and versatile method to optimize all-polymer solar cells and may help pave the route for this emerging system to overtake the state-of-the-art polymer/fullerene solar cells.

Polymer Pre‐Aggregation Enables Optimal Morphology and High Performance in All‐Polymer Solar Cells

“…To solve this morphological problem of N2200, researchers often use special processing conditions to suppress its aggregation, including hot spin‐coating from high‐boiling solvents . However, these approaches cause other serious problems, such as excessively mixed domains and low domain purity, which is detrimental to the charge mobility of polymers . In other words, the research community is mainly faced with two problems: either excessively large domain due to the highly crystalline nature of N2200 or overmixed domain when using the aforementioned special processing conditions.…”

Improved Charge Generation via Ultrafast Effective Hole‐Transfer in All‐Polymer Photovoltaic Blends with Large Highest Occupied Molecular Orbital (HOMO) Energy Offset and Proper Crystal Orientation

“…Materials Synthesis and Characterization : Polymer PTP8, PTQ‐1, PBDB‐T, and N2200 were synthesized according to the previous reports . UV–vis–NIR spectra were recorded on a Perkin Elmer model Lambda 750.…”

Cyclometalated Pt complex based random terpolymers as electron acceptors for all polymer solar cells

“…The most facile approach for the design and synthesis of efficient polymer acceptors is to alternately combine the above mentioned skeletons with another electron‐donating (D) or electron‐accepting (A) moiety and thus to construct D‐A or A‐A type conjugated copolymers . Among, the commercial copolymer N2200 poly[[ N , N ′‐bis(2‐octyldodecyl)‐naphthalene‐1,4,5,8‐bis(dicarboximide)‐2,6‐diyl]‐alt‐5,5′‐(2,2′‐bithiophene)](PDNIT2), which shows high electron mobility, high electron affinity, strong and broad light absorption, has been most widely studied as the currently most efficient polymer acceptors for all‐PSCs . For example, PCEs have been gradually increased from 3.2 to 5.3% in poly[4,8‐bis[5‐(2‐ethylhexyl)‐2‐thienyl]benzo[1,2‐ b :4,5‐ b ′]dithiophene‐alt‐(4‐(2‐ethylhexyl)‐3‐fluorothieno[3,4‐ b ]thiophene‐)‐2‐carboxylate‐2–6‐diyl)](PTB7‐Th):N2200‐based all‐PSCs .…”

“…Among, the commercial copolymer N2200 poly[[ N , N ′‐bis(2‐octyldodecyl)‐naphthalene‐1,4,5,8‐bis(dicarboximide)‐2,6‐diyl]‐alt‐5,5′‐(2,2′‐bithiophene)](PDNIT2), which shows high electron mobility, high electron affinity, strong and broad light absorption, has been most widely studied as the currently most efficient polymer acceptors for all‐PSCs . For example, PCEs have been gradually increased from 3.2 to 5.3% in poly[4,8‐bis[5‐(2‐ethylhexyl)‐2‐thienyl]benzo[1,2‐ b :4,5‐ b ′]dithiophene‐alt‐(4‐(2‐ethylhexyl)‐3‐fluorothieno[3,4‐ b ]thiophene‐)‐2‐carboxylate‐2–6‐diyl)](PTB7‐Th):N2200‐based all‐PSCs . Li and coworkers demonstrated a high PCE of 8.27% by employing fluorinated benzodithiophene‐alt‐benzotriazole copolymer J51 as donor and N2200 as acceptor polymer, which showed complementary absorptions in the vis–NIR region of 300–850 nm .…”