Highly stable and efficient NH 3 (aq)/C 4 H 10 S processed CuSCN bilayers for perovskite solar cells

CuSCN is a highly stable, easy to fabricate, and efficient hole transport layer. It is proposed to be a very stable alternative to its organic counterparts. The major research problem with this layer is the degradation action of polar solvents such as diethyl sulfide (DES) and dipropyl sulfide (DPS) on the organic absorber layers. Researchers are using various bilayers to overcome this issue. Here, we have proposed a bilayer of CuSCN with a different ammonia-based aqueous solvent. These bilayers exhibited better surface roughness values of ( ~ 26 nm) as compared to DES-processed CuSCN layers that inhibit roughness values of above (40 nm). These layers yielded smoother surfaces that are suitable for perovskite absorber layer growth. Moreover, we observed a light transmittance of up to 80% that can enable devices to harvest more especially from the lower wavelengths. Hole mobility rates of up to (87.51 cm 2 /Vs) and bulk carrier concentrations ranging between (10 13 to 10 15 ) /cm 3 makes them quite favorable for a good transport layer. Contact angle studies for the proposed bilayers showed that these layers still offer good hydrophobic properties up to (105 °C) while offering a better surface for a healthy absorber layer grain size. Further investigation of surface morphology shows that our proposed bilayers can function better on both Planar (n-i-p) and inverted planar (p-i-n) architectures. The successful demonstration of solution-processed CuSCN hole transport bilayers with perovskite absorber layer in Photoluminescence analysis shows how beneficial these layers can be for the fabrication of highly efficient and stable perovskite solar cells.