Achieving Both Enhanced Voltage and Current through Fine‐Tuning Molecular Backbone and Morphology Control in Organic Solar Cells

Abstract

It is a great challenge to simultaneously improve the two tangled parameters, open circuit voltage (Voc) and short circuit current density (Jsc) for organic solar cells (OSCs). Herein, such a challenge is addressed by a synergistic approach using fine‐tuning molecular backbone and morphology control simultaneously by a simple yet effective side chain modulation on the backbone of an acceptor–donor–acceptor (A–D–A)‐type acceptor. With this, two terthieno[3,2‐b]thiophene (3TT) based A–D–A‐type acceptors, 3TT‐OCIC with backbone modulation and 3TT‐CIC without such modification, are designed and synthesized. Compared with the controlled molecule 3TT‐CIC, 3TT‐OCIC shows power conversion efficiency (PCE) of 13.13% with improved Voc of 0.69 V and Jsc of 27.58 mA cm−2, corresponding to PCE of 12.15% with Voc of 0.65 V and Jsc of 27.04 mA cm−2 for 3TT‐CIC–based device. Furthermore, with effective near infrared absorption, 3TT‐OCIC is used as the rear subcell acceptor in a tandem device and gave an excellent PCE of 15.72%.

Asymmetric Alkoxy and Alkyl Substitution on Nonfullerene Acceptors Enabling High‐Performance Organic Solar Cells

“…To understand the reason for the dramatically reduced solubility (from Y6 to Y6-2O) caused by alkoxy substitution, we further carried out DFT calculations to investigate the conformational locking effect of the alkoxy groups on these molecules. [44][45][46] To simplify the calculations, we focus on the structure area with possible intramolecular conformational locking and compare two simplified units named T-O-IC and T-C-IC which are parts of Y6-2O and Y6 (Figure 2a). We set the optimized structure of T-O-IC and T-C-IC as the starting point.…”

Recent Progress on Broadband Organic Photodetectors and their Applications

“…Multilayered strategy is commonly applied to achieve high efficiency OPVs, called tandem OPVs, which connect the front and rear cells by the recombination layers. [86][87][88] Recently, multilayered strategy has been employed to build broadband photodetectors with high performance, including OPDs and perovskite/organic BHJ hybrid photodetectors. [89][90][91][92][93][94] The advantages of multilayered photodetectors can be summarized as: i) superimposing the photon harvesting of each single layer, which is conducive to broadening the spectral response and strengthening the photoresponse of the photodetectors; ii) suppressing the J d of photodetectors due to the suppressed charge injection, which is beneficial for increasing the D* of photodetectors.…”

High-Performance Ternary Organic Solar Cells Enabled by Synergizing Fullerene and Non-fullerene Acceptors

“…In other word, the incorporation of FA can disperse the mass aggregation of NFAs and then form a suitable domain size in ternary OSCs to balance charge carrier generation and transport. [41][42][43] Based on the ternary strategy involving a FA and an NFA, Lu et al [1,2,5]thiadiazole-4,7-diyl) di(thiophen-2yl)}) or PFTBDT-BZS (polymer containing FBDT [4-alkyl-3,5difluorophenyl group was introduced as the lateral side chain to the benzodithiophene (BDT) unit] as the donor unit, benzothiadiazole as the acceptor unit, and thiophene as the spacer) as a donor to fabricate ternary OPVs with the overall D:A ratio of 1:2, respectively. Both PPBDTBT: ITIC 44 and PFTBDT-BZS: ITIC 45 binary OPVs exhibit limited J sc of 13.00 and 12.54 mA cm À2 , as well as the unsatisfied FFs of 63% and 56%, respectively, which can be attributed to the large phase separation due to the mass aggregation of ITIC, restricting the development of J sc and FF.…”