Solution‐Processed Organic Solar Cells with High Open‐Circuit Voltage of 1.3 V and Low Non‐Radiative Voltage Loss of 0.16 V

• DOI: 10.1002/adma.202002122
• Publication Date: 2020-08-26T18:54:34Z
• Authors: Ning An; Yunhao Cai; Hongbo Wu; Ailing Tang; Kangning Zhang; Xiaotao Hao; Zaifei Ma; Qiang Guo; Hwa Sook Ryu; Han Young Woo; Yanming Sun; Erjun Zhou
• Keywords: Open-circuit voltage; Acceptor; Electron acceptor

Compared with inorganic or perovskite solar cells, the relatively large non-radiative recombination voltage losses (ΔVnon-rad ) in organic cells (OSCs) limit improvement of open-circuit (Voc ). Herein, OSCs are fabricated by adopting two pairs D-π-A polymers (PBT1-C/PBT1-C-2Cl and PBDB-T/PBDB-T-2Cl) as electron donors a wide-bandgap molecule BTA3 acceptor. In these blends, charge-transfer state energy (ECT high 1.70-1.76 eV is achieved, leading to small energetic differences between singlet excited states (ΔECT ≈ 0.1 eV). addition, after introducing chlorine atoms into π-bridge side chain benzodithiophene (BDT) unit, electroluminescence external quantum efficiencies 1.9 × 10-3 1.0 realized based on PBTI-C-2Cl PBDB-T-2Cl, respectively. Their corresponding ΔVnon-rad 0.16 0.17 V, which lower than those analog without atom (0.21 0.24 V for PBT1-C PBDB-T, respectively), resulting Voc 1.3 V. The achieved PBT1-C-2Cl:BTA3 thought represent best values solution-processed reported literature so far.