Highly Efficient Wide Bandgap Perovskite Solar Cells With Tunneling Junction by Self-Assembled 2D Dielectric Layer.

Reducing non-radiative recombination and addressing band alignment mismatches at interfaces remain major challenges in achieving high-performance wide-bandgap perovskite solar cells. This study proposes the self-organization of a thin two-dimensional (2D) perovskite BA 2 PbBr 4 layer beneath a wide-bandgap three-dimensional (3D) perovskite Cs 0.17 FA 0.83 Pb(I 0.6 Br 0.4 ) 3 , forming a 2D/3D bilayer structure on a tin oxide (SnO 2 ) layer. This process is driven by interactions between the oxygen vacancies on the SnO 2 surface and hydrogen atoms of the n-butylammonium cation, aiding the self-assembly of the BA 2 PbBr 4 2D layer. The 2D perovskite acts as a tunneling layer between SnO 2 and the 3D perovskite, neutralizing the energy level mismatch and reducing non-radiative recombination. This results in high power conversion efficiencies of 21.54% and 19.16% for wide-bandgap perovskite solar cells with bandgaps of 1.7 and 1.8 eV, with open-circuit voltages over 1.3 V under 1-Sun illumination. Furthermore, an impressive efficiency of over 43% is achieved under indoor conditions, specifically under 200 lux white light-emitting diode light, yielding an output voltage exceeding 1 V. The device also demonstrates enhanced stability, lasting up to 1,200 hours.