Inverted organic photovoltaics with a solution-processed ZnO/MgO electron transport bilayer

Abstract

Electron transport layers (ETLs) have been instrumental in breaking the efficiency boundaries of solution-processed photovoltaics. In particular, bilayer ETLs with an MgO top component have afforded tremendous success in various...

Attributes of High-Performance Electron Transport Layers for Perovskite Solar Cells on Flexible PET versus on Glass

“…The ZnO/SnO 2 -based cells delivered smaller reverse current showing better blocking behavior and lower defect densities. 43 , 44 Composite ETLs, in fact, as in this case, reduce both pinholes and surface trap states which can be present at some of the interfaces of single ETLs 34 , 37 − 39 in addition to the reduction of charge recombination at interfaces, 45 suggested by higher shunt resistance compared to the cells with SnO 2 only. 38 , 46 − 48 SEM images of the perovskite films deposited on SnO 2 and ZnO/SnO 2 ETLs ( Figure 4 ) reveal that also the bulk perovskite film improves when growing over the composite ETL.…”

“… 37 , 38 The ETL overlayer has also been shown to reduce the work function of the composite electrode thus helping improve electron extraction. 39 …”

“…A ZnO–SnO 2 -cascaded ETL was employed to improve the interface stability and efficiency of PSCs . Dagar et al developed all-solution-processed ETLs: SnO 2 /meso-TiO 2 bilayers on flexible substrates and SnO 2 /MgO, SnO 2 /Al 2 O 3 bilayers on rigid substrates, improving PCEs significantly ,, by enhancing wettability, rectification ratios, and shunt resistances. , The ETL overlayer has also been shown to reduce the work function of the composite electrode thus helping improve electron extraction …”

Inverted organic photovoltaics with a solution-processed Mg-doped ZnO electron transport layer annealed at 150 °C

“…Another effective strategy is to apply a modifying interlayer between ZnO and the active layer. 28 However, the above processes require additional steps to obtain the final ETL. When considering the fabrication of solution-processed photovoltaics (PVs) at an industrial scale, a more streamlined approach is desirable or even required.…”

“…Having used MgO successfully to form a bilayer ETL with ZnO in previous work 28 (where a non-uniform ultrathin MgO layer z 10 nm was inserted between ZnO and the active layer) we were interested to test whether direct addition of the MgO precursor to the ZnO precursor solution is a viable route to form a Mg-doped ZnO ETL for application to OPVs. Such an approach would obviously favour scalability at an industrial level, because it requires fewer steps and eliminates the need to control the MgO layer thickness to a few nm.…”