Several approaches, including the use of small molecule acceptors, novel polymer structures, and tandem cell structures, have been adopted to prepare polymer solar cells displaying high power conversion efficiencies (PCEs). The application of ternary blends as the active layer for polymer solar cells—for which the absorption spectra can be tuned by varying the composition ratios of components—is another facile approach toward optimizing the PCEs of devices. The selection of suitable ternary blends active layer often relies on intuition and remains a formidable challenge. Here, we adopted a systemic approach of not only using the same donor chemical units in the two donor-acceptor (D/A) conjugated polymers with complementary light absorption (energy band gaps) but also varying the side chains architectures as a means of tuning the packing of these semi-planar conjugated polymers, thereby influencing the carrier transport and optimizing the PCE. We employed linear, branch and mixed linear-and-branch side-chain attached benzooxadiazole (BO) as the acceptor (A) units in poly[benzodithiophene-thiophene-benzooxadiazole] (PBDTTBO) conjugated polymers and monitored their interactions with poly[benzodithiophene-fluorothienothiophene] (PTB7-TH), both of which featured the same benzodithiophene (BDTT) donor (D) units. We found that incorporating a minor amount (10%) of D/A conjugated PBDTTBO with such side chains into the PTB7-TH with a fullerene allowed us to tune the packing of the two polymers and, thereby, enhance the PCEs of corresponding ternary blend devices; the PCE of the ternary blend device incorporating PBDTTBO with two branched-side chains, PTB7-TH, and PC₇₁BM increased to 11.4% from 9.0% for the device incorporating only the binary blend of PTB7-TH and PC₇₁BM—a relative increase of more than 25%. This approach of using side chain engineering to tune the structure of a minor conjugated polymer and, thus, influence the packing of another major conjugated polymer that features the same donor chemical units appears to be an effective means of preparing highly efficient polymer cells.

已经采用了几种方法，包括使用小分子受体，新颖的聚合物结构和串联电池结构，来制备表现出高功率转换效率（PCE）的聚合物太阳能电池。将三元共混物用作聚合物太阳能电池的活性层（可通过更改组件的组成比来调整吸收光谱）是优化器件PCE的另一种简便方法。合适的三元共混物活性层的选择通常取决于直觉，并且仍然是一个艰巨的挑战。这里，我们采用系统的方法，不仅在两种具有互补光吸收（能带隙）的施主-受体（D / A）共轭聚合物中使用相同的施主化学单元，而且还通过改变侧链结构作为调整填料的方法这些半平面共轭聚合物的结构，从而影响载流子传输并优化PCE。我们在聚[苯并二噻吩-噻吩-苯并恶二唑]（PBDTTBO）共轭聚合物中采用线性，分支和混合的直链和支链侧链连接的苯并恶二唑（BO）作为受体（A）单元，并监测它们与聚[苯并二噻吩-氟噻吩噻吩]（PTB7-TH），两者均具有相同的苯并二噻吩（BDTT）供体（D）单元。我们发现，将少量（10％）具有此类侧链的D / A共轭PBDTTBO与富勒烯掺入PTB7-TH中使我们能够调节两种聚合物的堆积，从而增强相应三元共混物的PCE设备; 三元混合设备的PCE结合了PBDTTBO和两个分支侧链PTB7-TH和PC对于仅包含PTB7-TH和PC ₇₁ BM的二元共混物的设备，₇₁ BM从9.0％增加到11.4％，相对增加了25％以上。这种使用侧链工程技术来调节次要共轭聚合物的结构，从而影响另一个具有相同供体化学单元的主要共轭聚合物的堆积的方法，似乎是制备高效聚合物电池的有效手段。