18.77 % Efficiency Organic Solar Cells Promoted by Aqueous Solution Processed Cobalt(II) Acetate Hole Transporting Layer

Abstract

A robust hole transporting layer (HTL), using the cost‐effective Cobalt(II) acetate tetrahydrate (Co(OAc)2⋅4 H2O) as the precursor, was simply processed from its aqueous solution followed by thermal annealing (TA) and UV‐ozone (UVO) treatments. The TA treatment induced the loss of crystal water followed by oxidization of Co(OAc)2⋅4 H2O precursor, which increased the work function. However, TA treatment differently realize a high work function and ideal morphology for charge extraction. The resulting problems could be circumvented easily by additional UVO treatment, which also enhanced the conductivity and lowered the resistance for charge transport. The optimal condition was found to be a low temperature TA (150 °C) followed by simple UVO, where the crystal water in Co(OAc)2⋅4 H2O was removed fully and the HTL surface was anchored by substantial hydroxy groups. Using PM6 as the polymer donor and L8‐BO as the electron acceptor, a record high PCE of 18.77 % of the binary blend OSCs was achieved, higher than the common PEDOT:PSS‐based solar cell devices (18.02 %).

Boosting the Efficiency of Non-fullerene Organic Solar Cells via a Simple Cathode Modification Method

“…After the development of the milestone small molecule acceptor, Y6, and its derivatives, interfacial engineering, in particular, the research on ETLs with compatible properties has been trending. New ETL materials have been synthesized and adopted, which promoted both the PCE and stability of the Y6-based devices. − Behind the improved device performance was progress of the ETL made from the material design and synthesis that leads to novel material structures. − However, compared to the doping strategy widely used in improving the property of the hole transport layers (HTLs) that also leads to outstanding results, − the chemistry input in material synthesis could be cost inefficient and should be accompanied by exploring methods of utilizing existing ETL materials.…”

Boosting the overall stability of organic solar cells by crosslinking vinyl-functionalized polymer derived from PM6

“…[1][2][3] Due to the rapid development of non-fullerene small molecule acceptors (SMAs) with a narrow band gap and high absorption, power conversion efficiencies (PCEs) of organic solar cells have exceeded 18%. [4][5][6][7][8][9][10] In particular, as a unique molecular design of A-D-A 0 -D-A, the electron-deficient-core-based SMAs have been rapidly developed. 5,[11][12][13][14][15][16][17] For example, the most typical A-DA 0 D-A type SMA is the Y6 small molecule developed by Zou combined with a typical D-A polymer donor with an outstanding PCE of 15.7%.…”

A linear 2D-conjugated polymer based on 4,8-bis(4-chloro-5-tripropylsilyl-thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene (BDT-T-SiCl) for low voltage loss organic photovoltaics

“…[8][9][10][11][12] With the continuous development of new photovoltaic materials and device engineering, the power conversion efficiency (PCE) of single junction OPVs based on polymer:non-fullerene acceptors (NFAs) has exceeded 18%. [13][14][15][16] In terms of the three important parameters of OPVs, the shortcircuit current density (J SC ) has reached 28 mA cm À2 , and the ll factor (FF) exceeds 80%, 17,18 but the open-circuit voltage (V OC ) is usually limited to below 0.9 V. Compared with perovskite solar cells (PSCs), the V OC of OPVs is the least among the three parameters mainly because of the larger voltage loss (V loss ) of organic materials, typically exceeding 0.6 V. [19][20][21][22][23] To meet the needs of different application scenarios and the rapid development of the Internet of Things (IoT), NFAs with different optoelectronic properties have been synthesized. 24,25 Narrow-bandgap materials such as Y6, BTP-eC9, Y6-1O, etc.…”