Investigating the Grading Profile in Dion–Jacobson‐2D Layered CsSnI _{3− <i>x</i>} Br _<i>x</i> ‐Based Heterostructure Device for Superior Photovoltaic Performance

A perovskite solar cell device is designed in which 2D perovskite with Dion–Jacobson (DJ) phase incorporated on prime photoactive 3D CsSnI 3− x Br x with the cell configuration FTO/CeO 2 /PeDAMA 4 Pb 5 I 16 /CsSnI 3− x Br x /CFTS/Au. The linear and parabolic grading of the absorber CsSnI 3− x Br x along its depth in purposed device structure is performed by changing ‘Br’ composition ( x ) from 0 to 3. The impact of varying prime absorber thickness, composition of ‘Br’ (0–3), and bowing factor (0–1) on the linearly and parabolic‐graded photovoltaic parameters are analyzed. The effect of series and shunt resistance, defect density of the CsSnI 3− x Br x absorber, back contact metal work function, overall device operating temperature, and the variation of hole transport layers and electron transport layers are also extensively studied under both linear and parabolic grading conditions. The present detailed investigation and comprehensive analysis of the linearand parabolicgraded outcome revealed the superior photovoltaic performance with exceptionally impressive power conversion efficiency ≈36.96% at room temperature condition delivered by the purposed device along with excellent parameters V oc ≈ 1.28 V, J sc ≈ 35.83 mA cm −2 , and fill factor ≈80.40% for 1 μm thick CsSnI 3− x Br x absorber at composition value x = 0 at CsSnI 3− x Br x /HTL interface. The outcome of the present work categorically suggested the effect of introducing the DJ‐2D perovskite on breaching the Shockley–Queisser limit.