Engineering topics
Publications and source records attributed to Yao, Huatong.
This is the first time alkylthio chains are employed on Y6-like NFAs to achieve organic solar cells of power conversion efficiency higher than 16%.
Abstract The conventional method to prepare bulk‐heterojunction organic photovoltaics (OPVs) is a one‐step method from the blend solution of donor and acceptor materials, known as blend‐casting (BC). Recently, an alternative method was demonstrated to achieve high efficiencies (13%) comparable to state‐of‐the‐art BC devices. This two‐step‐coating method, known as “sequential processing,” (SqP) involves sequential deposition of the donor and then the acceptor from two orthogonal solvents. However, the requirement of orthogonal solvents to process the donor and acceptor constrains the choice of materials and processing solvents. In this paper, an improved version of SqP method without the need for using orthogonal solvents is reported. The success is based on donor polymers with strong temperature‐dependent aggregation properties whose solution can be processed at a high temperature, but the resulting film becomes completely insoluble at room temperature, which allows for the processing of overlying acceptors from a wide range of nonorthogonal solvents. With this approach, efficient SqP OPVs is demonstrated based on a range of donor/acceptor materials and processing solvents, and, in every single case, SqP OPVs can outperform their BC counterparts. The results broaden the solvent choices and open a much larger window to optimize the processing parameters of SqP method.
Abstract Semitransparent organic solar cells have great potential for building integrated photovoltaics and power‐generating windows owing to their advantages of light weight, mechanical flexibility, and color tunability. However, the performance of previous semitransparent organic solar cells have been limited by their relatively weak optical absorptions. In this paper, an efficient nonfullerene semitransparent tandem organic solar cell that exhibits a broad absorption from 300 to 1000 nm is reported. The rear subcell is based on a narrow‐bandgap nonfullerene acceptor named IEICS‐4F that exhibits a strong crystallinity and high electron mobility. As a result, the IEICS‐4F‐based single‐junction opaque and semitransparent organic solar cells yield high efficiencies of 10.3% and 7.5%, respectively. To further enhance light harvesting of the single‐junction semitransparent organic solar cells while maintaining a decent transmittance, a semitransparent tandem organic solar cell is fabricated by incorporating a medium‐bandgap P3TEA:FTTB‐PDI 4 blend as the front subcell. A high efficiency of 10.5% is recorded with an average transmittance of 20%.