Design and simulation investigations on charge transport layers-free in lead-free three absorber layer all-perovskite solar cells

Abstract The multiple absorber layer perovskite solar cells (PSCs) with charge transport layers-free (CTLs-free) have drawn widespread research interest due to their simplified architecture and promising photoelectric characteristics. Under the circumstances, the novel design of CTLs-free inversion PSCs with stable and nontoxic three absorber layers (triple Cs 3 Bi 2 I 9 , single MASnI 3 , double Cs 2 TiBr 6 ) as optical-harvester has been numerically simulated by utilizing wxAMPS simulation software and achieved high power conversion efficiency (PCE) of 14.8834%. This is owing to the innovative architecture of PSCs favors efficient transport and extraction of more holes and the slender band gap MASnI 3 extends the absorption spectrum to the near-infrared periphery compared with the two absorber layers architecture of PSCs. Moreover, the performance of the device with p-type-Cs 3 Bi 2 I 9 /p-type-MASnI 3 /n-type-Cs 2 TiBr 6 architecture is superior to the one with the p-type-Cs 3 Bi 2 I 9 /n-type-MASnI 3 /n-type-Cs 2 TiBr 6 architecture due to less carrier recombination and higher carrier life time inside the absorber layers. The simulation results reveal that Cs 2 TiF 6 double perovskite material stands out as the best alternative. Additionally, an excellent PCE of 21.4530% can be obtained with the thicker MASnI 3 absorber layer thickness (0.4 µm). Lastly, the highest-performance photovoltaic devices (28.6193%) can be created with the optimized perovskite doping density of around E15 cm 3 (Cs 3 Bi 2 I 9 ), E18 cm 3 (MASnI 3 ), and 1.5E19 cm 3 (Cs 2 TiBr 6 ). This work manifests that the proposed CTLs-free PSCs with multi-absorber layers shall be a relevant reference for forward applications in electro-optical and optoelectronic devices. Graphical Abstract