Open-circuit and short-circuit loss management in wide-gap perovskite p-i-n solar cells
Pietro Caprioglio, Joel A. Smith, Robert D. J. Oliver, Akash Dasgupta, Saqlain Choudhary, Michael D. Farrar, Alexandra J. Ramadan, Yen‐Hung Lin, M. Greyson Christoforo, James M. Ball, Jonas Diekmann, Jarla Thiesbrummel, Karl‐Augustin Zaininger, Xinyi Shen, Michael B. Johnston, Dieter Neher, Martin Stolterfoht, Henry J. Snaith
Abstract
Abstract In this work, we couple theoretical and experimental approaches to understand and reduce the losses of wide bandgap Br-rich perovskite pin devices at open-circuit voltage (V OC ) and short-circuit current (J SC ) conditions. A mismatch between the internal quasi-Fermi level splitting (QFLS) and the external V OC is detrimental for these devices. We demonstrate that modifying the perovskite top-surface with guanidinium-Br and imidazolium-Br forms a low-dimensional perovskite phase at the n -interface, suppressing the QFLS-V OC mismatch, and boosting the V OC . Concurrently, the use of an ionic interlayer or a self-assembled monolayer at the p -interface reduces the inferred field screening induced by mobile ions at J SC , promoting charge extraction and raising the J SC . The combination of the n- and p- type optimizations allows us to approach the thermodynamic potential of the perovskite absorber layer, resulting in 1 cm 2 devices with performance parameters of V OC s up to 1.29 V, fill factors above 80% and J SC s up to 17 mA/cm 2 , in addition to a thermal stability T 80 lifetime of more than 3500 h at 85 °C.