Interlayer Cross‐Linked 2D Perovskite Solar Cell with Uniform Phase Distribution and Increased Exciton Coupling. Issue 4 (29th January 2020) - Wang, Han
Abstract : A nonuniform vertical phase distribution and thick insulating barrier can decrease the energy transfer between slices in layered perovskite solar cells (PSCs). Herein, an interlayer cross‐linked Dion–Jacobson (DJ)‐type 2D PSC with 1, 4‐butanediamine (BDA) as a short‐chain insulating spacer [formula: (BDA)MA n −1 Pb n I3 n + 1 ] is reported and demonstrates the vertical phase becoming uniform with enhanced exciton coupling, leading to reduced nonradiative recombination. For n = 1 pure phase perovskite, an exciton binding energy of the DJ phase (BDA)PbI4 is ≈142 meV, much smaller than ≈435 meV of Ruddlesden–Popper (RP) phase (BA)2 PbI4 ( n = 1) perovskite, indicative of exciton‐coupling‐induced efficient energy transfer. Therefore, the high energy emission peaks for the (BDA)MA3 Pb4 I13 film are not observed even in liquid nitrogen temperature (78 K), which can be distinguished from that of the (BA)2 MA3 Pb4 I13 film. Energy transfer between 2D slices of (BDA)MA3 Pb4 I13 is 100 times faster than that of (BA)2 MA3 Pb4 I13 . The uniform vertical distribution and exciton coupling mitigate nonradiative energy loss and significantly improve V oc in inverted structures (PEDOT:PSS/(BDA)MA3 Pb4 I13 /PCBM/bathocuproine/Ag) to ≈1.15 V and the control n ‐butylammonium‐based device demonstrates only a V oc = ≈1 V. It is believed that the results would provide a deep understanding of exciton coupling in hybrid multicomponent quantum wells. Abstract : Dion–Jacobson (DJ) phase 2D perovskite presents a much stronger interlayer interaction, and thus, it is beneficial for efficient charge transport a cross neighboring inorganic layers. With ultrafast laser spectroscopy, uniform distribution and smoother energy landscape are demonstrated in the vertical direction of DJ perovskite films, which can be distinguished from graded composition in Ruddlesden–Popper phase perovskite.