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

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 CsBiI, single MASnI, double CsTiBr) 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 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-CsBiI/p-type-MASnI/n-type-CsTiBr architecture is superior to the one with the p-type-CsBiI/n-type-MASnI/n-type-CsTiBr architecture due to less carrier recombination and higher carrier life time inside the absorber layers. The simulation results reveal that CsTiF double perovskite material stands out as the best alternative. Additionally, an excellent PCE of 21.4530% can be obtained with the thicker MASnI 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 (CsBiI), E18 cm (MASnI), and 1.5E19 cm (CsTiBr). 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.