Vacuum‐Free, All‐Solution, and All‐Air Processed Organic Photovoltaics with over 11% Efficiency and Promoted Stability Using Layer‐by‐Layer Codoped Polymeric Electrodes

Abstract

Nonfullerene organic photovoltaics (OPVs) have achieved a breakthrough in pushing the efficiency beyond 15%. Although this sheds light on OPV commercialization, the high cost associated with the scalable device fabrications remains a giant challenge. Herein, a vacuum‐free, all‐solution and all‐air processed OPV is reported that yields 11.12% efficiency with a fill factor of 0.725, due to the usages of high‐merit polymeric electrodes and modified active blends. The design principle toward the high‐merit electrodes is to induce heavy acid doping into the matrices for a raised carrier concentration and mobility, make a large removal of insulating components in the whole matrices rather than surfaces, and restrain the formation of large‐domain aggregates. A unique layer‐by‐layer doping is developed to enable the polymeric electrodes with record‐high trade‐offs between optical transmittance and electrical conductivity. Moreover, solvent vapor annealing is proposed to boost device efficiency and it has the advantages of finely adjusting the active blend morphology and raising the electron mobility. The resulting devices are highly efficient and most (≈91%) of the initial efficiency are maintained in 30 day storage. This work indicates bright future for making cost‐effective all‐solution processed OPVs in air.

Stretchable ITO‐Free Organic Solar Cells with Intrinsic Anti‐Reflection Substrate for High‐Efficiency Outdoor and Indoor Energy Harvesting

“…[ 21–30 ] Intensive research efforts have been targeted at flexible OPVs, in particular indium tin oxide (ITO)‐free flexible transparent electrodes (FTEs), such as conducting polymer, metal nanowires, and graphene, which enabled a PCE of 15%. [ 31–39 ]…”

Evaporation‐Free Organic Solar Cells with High Efficiency Enabled by Dry and Nonimmersive Sintering Strategy

“…The J sc and V oc discrepancy of the evaporation‐free devices fabricated in different institutes originates from the raw material (active layer) difference since their evaporated counterparts show identical trend (Figure S16 and Table S3, Supporting Information). To the best our knowledge, the PCE of our evaporation‐free devices outperforms all of the reported devices with a solution‐processed top electrode including PEDOT:PSS, [ 5,23 ] Ag NWs, [ 3,4,22,32,33 ] Ag NPs/inks, [ 19,34–37 ] Ag pastes, [ 38,39 ] and graphene [ 21 ] (Figure 3f).…”

“…f) The PCE comparison of OSCs between this work and other works with a solution processed top electrode (The active layer materials information of some high performance OSCs are provided). [ 3–5,19,21–23,32–39 ]…”

“…For example, Nie et al reported a fully solution-solution processed OSCs employing a modified PEDOT:PSS as top cathode. [23] The device delivered a PCE of 11.12% with contrast to 13.42% of its evaporated counterpart. The major difference stems from the Jsc (19.55 mA cm -2 and 22.66 mA cm -2 for solution process and evaporation, respectively).…”

“…e) Stabilized photocurrent of the evaporation-based and evaporation-free devices at maximum power point. f) The PCE comparison of OSCs between this work and other works with a solution processed top electrode (The activelayer materials information of some high performance OSCs are provided) [3][4][5]19,[21][22][23][32][33][34][35][36][37][38][39].…”