The Role of Bulk and Interface Recombination in High‐Efficiency Low‐Dimensional Perovskite Solar Cells. Issue 30 (5th June 2019)

• Record Type: Journal Article
• Authors: Zhang, Shanshan; Hosseini, Seyed M.; Gunder, René; Petsiuk, Andrei; Caprioglio, Pietro; Wolff, Christian M.; Shoaee, Safa; Meredith, Paul; Schorr, Susan; Unold, Thomas; Burn, Paul L.; Neher, Dieter; Stolterfoht, Martin
• Is Part Of: Advanced materials. Volume 31:Issue 30(2019)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2019-06-05
• Subjects: 2D perovskites -- interface recombination -- perovskite solar cells -- photoluminescence -- VOC loss; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.201901090
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: 2D Ruddlesden–Popper perovskite (RPP) solar cells have excellent environmental stability. However, the power conversion efficiency (PCE) of RPP cells remains inferior to 3D perovskite‐based cells. Herein, 2D (CH3 (CH2 )3 NH3 )2 (CH3 NH3 ) n −1 Pb n I3 n +1 perovskite cells with different numbers of [PbI6 ] 4− sheets ( n = 2–4) are analyzed. Photoluminescence quantum yield (PLQY) measurements show that nonradiative open‐circuit voltage ( V OC ) losses outweigh radiative losses in materials with n > 2. The n = 3 and n = 4 films exhibit a higher PLQY than the standard 3D methylammonium lead iodide perovskite although this is accompanied by increased interfacial recombination at the top perovskite/C60 interface. This tradeoff results in a similar PLQY in all devices, including the n = 2 system where the perovskite bulk dominates the recombination properties of the cell. In most cases the quasi‐Fermi level splitting matches the device V OC within 20 meV, which indicates minimal recombination losses at the metal contacts. The results show that poor charge transport rather than exciton dissociation is the primary reason for the reduction in fill factor of the RPP devices. Optimized n = 4 RPP solar cells had PCEs of 13% with significant potential for further improvements. Abstract : The factors affecting the V OC in 2D perovskite cells with different [PbI6 ] 4− layer sheets ( n = 2–4) are elucidated. Nonradiative recombination at the perovskite/C60 interface is found to dominate except for the n = 2 system where the bulk recombination determines the properties of the cell. Substantial V OC gains through suppression of interfacial recombination at the top interface are expected.