Qiaoshi An

Bio: Qiaoshi An is an academic researcher from Beijing Jiaotong University. The author has contributed to research in topics: Polymer solar cell & Ternary operation. The author has an hindex of 43, co-authored 81 publications receiving 5639 citations. Previous affiliations of Qiaoshi An include Beijing Institute of Technology & Chinese Ministry of Education.

Versatile ternary organic solar cells: a critical review

Abstract: The power conversion efficiency (PCE) of organic solar cells has been constantly refreshed in the past ten years from 4% up to 11% due to the contribution from the chemists on novel materials and the physicists on device engineering. For practical applications, a single bulk heterojunction structure may be the best candidate due to the cell with a high PCE, easy fabrication and low cost. Recently, ternary solar cells have attracted much attention due to enhanced photon harvesting by using absorption spectral or energy level complementary materials as the second donor or acceptor based on a single bulk heterojunction structure. For better promoting the development of ternary solar cells, we summarize the recent progress of ternary solar cells and try our best to concise out the scientific issues in preparing high performance ternary solar cells.

Asymmetrical Ladder‐Type Donor‐Induced Polar Small Molecule Acceptor to Promote Fill Factors Approaching 77% for High‐Performance Nonfullerene Polymer Solar Cells

Abstract: In this work, an effectual strategy of constructing polar small molecule acceptors (SMAs) to promote fill factor (FF) of nonfullerene polymer solar cells (PSCs) is first reported. Three asymmetrical SMAs of IDT6CN, IDT6CN-Th, and IDT6CN-M, which own large dipole moments, are designed and synthesized. The PSCs based on three polar SMAs exhibit apparently higher FFs compared with their symmetrical analogues. The asymmetrical design strategy accompanied with side chain and end group engineering makes IDT6CN-Th- and IDT6CN-M-based nonfullerene PSCs achieve high power conversion efficiency with FFs approaching 77%.

Alloy-like ternary polymer solar cells with over 17.2% efficiency

Abstract: Ternary strategy has been considered as an efficient method to achieve high performance polymer solar cells (PSCs). A power conversion efficiency (PCE) of 17.22% is achieved in the optimized ternary PSCs with 10 wt% MF1 in acceptors. The over 8% PCE improvement by employing ternary strategy is attributed to the simultaneously increased JSC of 25.68 mA cm−2, VOC of 0.853 V and FF of 78.61% compared with Y6 based binary PSCs. The good compatibility of MF1 and Y6 can be confirmed from Raman mapping, contact angle, cyclic voltammetry and morphology, which is the prerequisite to form alloy-like state. Electron mobility in ternary active layers strongly depends on MF1 content in acceptors due to the different lowest unoccupied molecular orbital (LUMO) levels of Y6 and MF1, which can well explain the wave-like varied FF of ternary PSCs. The third-party certified PCE of 16.8% should be one of the highest values for single bulk heterojunction PSCs. This work provides sufficient references for selecting materials to achieve efficient ternary PSCs.

Ternary nonfullerene polymer solar cells with efficiency >13.7% by integrating the advantages of the materials and two binary cells

Abstract: Highly efficient ternary polymer solar cells (PSCs) are fabricated from two well-compatible small molecular nonfullerene acceptors (INPIC-4F and MeIC1) and one polymer donor, PBDB-T. The power conversion efficiency (PCE) of the INPIC-4F or MeIC1 based binary PSCs reaches 12.55% and 11.53%. Based on these efficient binary PSCs, a high PCE of 13.73% is achieved in the ternary PSCs with 50 wt% MeIC1 in the acceptors, resulting from the simultaneously improved short circuit current (JSC) of 21.86 mA cm−2, open circuit voltage (VOC) of 0.88 V and fill factor (FF) of 71.39%. The PCE improvement of the ternary PSCs should be mainly attributed to the simultaneously optimized photon harvesting and film morphology of the ternary active layers. This result may provide more in-depth insight into the material selection criteria for fabricating highly efficient ternary PSCs: (i) the complementary absorption spectra and good compatibility of the used materials; (ii) the complementary photovoltaic parameters of the corresponding two binary PSCs.

Over 16% efficiency organic photovoltaic cells enabled by a chlorinated acceptor with increased open-circuit voltages

Abstract: Broadening the optical absorption of organic photovoltaic (OPV) materials by enhancing the intramolecular push-pull effect is a general and effective method to improve the power conversion efficiencies of OPV cells. However, in terms of the electron acceptors, the most common molecular design strategy of halogenation usually results in down-shifted molecular energy levels, thereby leading to decreased open-circuit voltages in the devices. Herein, we report a chlorinated non-fullerene acceptor, which exhibits an extended optical absorption and meanwhile displays a higher voltage than its fluorinated counterpart in the devices. This unexpected phenomenon can be ascribed to the reduced non-radiative energy loss (0.206 eV). Due to the simultaneously improved short-circuit current density and open-circuit voltage, a high efficiency of 16.5% is achieved. This study demonstrates that finely tuning the OPV materials to reduce the bandgap-voltage offset has great potential for boosting the efficiency. Halogenation has proved an effective strategy to improve the power conversion efficiencies of organic solar cells but it usually leads to lower open-circuit voltages. Here, Cui et al. unexpectedly obtain higher open-circuit voltages and achieve a record high PCE of 16.5% by chlorination.

Nonfullerene Acceptor Molecules for Bulk Heterojunction Organic Solar Cells

Abstract: The bulk-heterojunction blend of an electron donor and an electron acceptor material is the key component in a solution-processed organic photovoltaic device. In the past decades, a p-type conjugated polymer and an n-type fullerene derivative have been the most commonly used electron donor and electron acceptor, respectively. While most advances of the device performance come from the design of new polymer donors, fullerene derivatives have almost been exclusively used as electron acceptors in organic photovoltaics. Recently, nonfullerene acceptor materials, particularly small molecules and oligomers, have emerged as a promising alternative to replace fullerene derivatives. Compared to fullerenes, these new acceptors are generally synthesized from diversified, low-cost routes based on building block materials with extraordinary chemical, thermal, and photostability. The facile functionalization of these molecules affords excellent tunability to their optoelectronic and electrochemical properties. Within t...