Bandgap-engineered 2D Dion–Jacobson perovskite solar cells for high-efficiency outdoor and indoor operation

Perovskite solar cells designed for both outdoor and indoor operation still struggle to combine long-term stability, bandgap optimization, and efficiencies approaching the Shockley–Queisser (SQ) limit, especially when low-dimensional phases are employed. This study explores the potential of two-dimensional (2D) Dion–Jacobson perovskites as absorber materials for efficient and potentially stable single-junction solar cells operating under both AM1.5G and indoor white LED illumination. Unlike many conventional photovoltaic (PV) materials, these 2D perovskites offer ultrahigh environmental stability together with tunable optical properties, making them attractive for diverse illumination environments. Herein, we focus on (PDA)(MA) n–1 Pb n I 3n+1 structures with n = 2 and 4. A stepwise optimization workflow is implemented in which we first calibrate baseline devices to available experimental data, then systematically tune absorber thickness and bulk/interface defect densities to identify recombination-limited regimes. Next, we adjust band alignment via electron and hole transport layers and finally investigate series resistance contributions. This hierarchical approach clarifies how each parameter pushes the devices closer to their SQ limits. Under outdoor AM1.5G conditions, the n = 4 configuration emerges as the optimal structure, delivering superior device metrics, whereas under white LED illumination the wider-bandgap n = 2 configuration is intrinsically better matched to the indoor spectrum. By combining physics-based SCAPS-1D simulations with a structured optimization strategy, this work provides concrete design guidelines for 2D Dion–Jacobson perovskite solar cells tailored to both outdoor and indoor PV applications. • The study explores 2D Dion-Jacobson perovskite (2D-DJP) materials as bandgap tunable absorbers that can be utilized for both outdoor and indoor applications. • The performance of calibrated 2D-DJP solar cells is tested under standard AM1.5 G and white LED (2900K, 200 lux) illuminations. • Optimization of wide and narrow bandgap absorbers are provided through bulk, interface and series resistance optimization phases. • An optimized PCE of 23.18% under AM1.5G illumination is achieved for the narrow bandgap 2D-DJP cell. • An optimized PCE of 40.07% under warm LED illumination is achieved for the wide bandgap 2D-DJP cell.