This paper investigates the effect of incorporating a single-walled carbon nanotubes (SWCNTs) layer into the perovskite solar cell (PSC) structure as an effective technique to boost energy harvesting. The proposed PSC structure utilizes the SWCNTs layer underneath the CH3NH3PbI3 perovskite layer as an absorbing layer forming a novel design of (ITO/SnO2/CH3NH3PbI3/SWCNTs/NiOx/C) half tandem PSC structure. The suggested PSC structure is numerically analyzed using finite element method (FEM). The effects of varying thickness and doping concentration of the added layer and the material of rear electrode are investigated to maximize the power conversion efficiency (PCE) of the suggested PSC. Results of the 3D opto-electrical study and the energy bandgap analysis confirm that utilizing a 680 nm SWCNTs layer with doping concentration of 1.1 × 1020 cm-3 beneath a 150 nm perovskite layer enhances the PCE and short circuit current density (JSC) to $$25.6\%$$
25.6
%
and $$31.201 mA/{cm}^{2}$$
31.201
m
A
/
cm
2
, respectively due to the improving of the PSC absorption by $$27.65\%$$
27.65
%
. Higher performance of the proposed PSC has been achieved by using gold (Au) electrode instead of carbon (C) one, causing total enhancement of PCE and JSC of $$6.185\%$$
6.185
%
and $$9.18\;mA/cm^{2}$$
9.18
m
A
/
c
m
2
, respectively over their values for (ITO/SnO2/CH3NH3PbI3/P3HT/NiOx/C) structure reported in previously published literature. The proposed design can be considered as an efficient alternative to the conventional PSC owing to its higher performance and reduced toxicity.