Exceeding 14% Efficiency for Solution-Processed Tandem Organic Solar Cells Combining Fullerene- and Nonfullerene-Based Subcells with Complementary Absorption

Abstract

For a highly efficient tandem organic solar cell, it is important for the subcells to minimize the absorption overlap and generate high and balanced currents. Considering the strong absorption and high external quantum efficiency at the short wavelength, developing a highly efficient blend system with a wide-bandgap (WBG) polymer as the donor and a fullerene derivative as the acceptor in the front cell would be an effective strategy. However, it is a challenge to obtain a high short-current density (J sc ) for this blend system. Here, we develop a WBG polymer (PBD1) with an optical bandgap of 1.88 eV. The PBD1:PC 71 BM blend system with a thickness of 230 nm achieves a power conversion efficiency (PCE) of 9.8% with a high J sc of 14.6 mA cm −2 . When tandem devices are fabricated with PBD1:PC 71 BM in the front cell, a PCE of 14.2% with a high J sc of 12.3 mA cm −2 is achieved.

Recent Progress in Molecular Design of Fused Ring Electron Acceptors for Organic Solar Cells

“…An exceptional PCE over 14.9% with strong EQE covering 400–1000 nm was achieved for optimized tandem OSC . By replacing front sub‐cell with PBD1:PC 71 BM, Wong and co‐workers reported tandem OSC with PCE of 14.2% with a high FF of 0.72 . Another outstanding PCE of 14.64% was recently achieved using a narrow bandgap FREA T2 with an unsymmetrical π‐bridge in rear sub‐cell in a tandem configuration …”

Recent Advances Toward Highly Efficient Tandem Organic Solar Cells

“…(PM6), [98,100] [101] [80] [102] and so on, and the thieno[3,4-b]thiophene (TT)-based low-bandgap polymers, such as poly [4,8- [86] poly [4,8- [98,102,103] poly [4,8- (PBDTTT-C-T), [60,104,105] poly[4,8-bis(5-(2-ethylhexyl) thiophen-2-yl)benzo[1,2-b:4,5-b 0 ]dithiophene-co-thieno[3,4-b] thiophene-2-carboxylate] (PBDTTT-E-T), [80,95] and so on. Using the BDD-based wide bandgap polymers in the bottom cell and TTbased polymers in the top cell as well as pairing with desirable fullerenes and NFAs have been demonstrated to be a successful choice to construct high-performance tandem OSCs.…”

“…[33] To circumvent that, the pH neutral PEDOT:PSS analogues of m-PEDOT:PSS and highly conductive poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PH100) with high viscosity were used. [21,33,[38][39][40]58,70,[75][76][77]85,97,99,102,122,[127][128][129]132,138,144,164,208] Zhou and coworkers found that PEDOT:PSS with surfactant deposited on top of nonfullerene-based tandem OSCs might lead to chemical reaction between PEDOT:PSS and the NFA (IT-4F), which would be detrimental to the device performance. [100] To avoid the direct deposition of PEDOT:PSS on top of the active layer, they introduced a hydrogen molybdenum bronze (H x MoO 3 ) layer between the bottom active layer and PEDOT: PSS.…”

Asymmetric Wide‐Bandgap Polymers Simultaneously Improve the Open‐Circuit Voltage and Short‐Circuit Current for Organic Photovoltaics

“…Polymeric solar cells (PSCs) have received wide attention due to their low cost, light weight, and solution fabrication for large‐area devices . With the development of novel active layer materials, the short‐circuit current ( J SC ) and fill factors ( FFs ) have been achieved beyond 20 mA cm −2 and 80%, respectively.…”