On the origin of open-circuit voltage losses in flexible <i>n-i-p</i> perovskite solar cells Stefano Pisoni Martin Stolterfoht Johannes Löckinger Thierry Moser Yan Jiang Pietro Caprioglio Dieter Neher Stephan Buecheler Ayodhya N. Tiwari 10.6084/m9.figshare.8305928.v1 https://tandf.figshare.com/articles/journal_contribution/On_the_origin_of_open-circuit_voltage_losses_in_flexible_i_n-i-p_i_perovskite_solar_cells/8305928 <p>The possibility to manufacture perovskite solar cells (PSCs) at low temperatures paves the way to flexible and lightweight photovoltaic (PV) devices manufactured via high-throughput roll-to-roll processes. In order to achieve higher power conversion efficiencies, it is necessary to approach the radiative limit via suppression of non-radiative recombination losses. Herein, we performed a systematic voltage loss analysis for a typical low-temperature processed, flexible PSC in <i>n-i-p</i> configuration using vacuum deposited C<sub>60</sub> as electron transport layer (ETL) and two-step hybrid vacuum-solution deposition for CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> perovskite absorber. We identified the ETL/absorber interface as a bottleneck in relation to non-radiative recombination losses, the quasi-Fermi level splitting (QFLS) decreases from ~1.23 eV for the bare absorber, just ~90 meV below the radiative limit, to ~1.10 eV when C<sub>60</sub> is used as ETL. To effectively mitigate these voltage losses, we investigated different interfacial modifications via vacuum deposited interlayers (BCP, B4PyMPM, 3TPYMB, and LiF). An improvement in QFLS of ~30–40 meV is observed after interlayer deposition and confirmed by comparable improvements in the open-circuit voltage after implementation of these interfacial modifications in flexible PSCs. Further investigations on absorber/hole transport layer (HTL) interface point out the detrimental role of dopants in Spiro-OMeTAD film (widely employed HTL in the community) as recombination centers upon oxidation and light exposure.</p> 2019-06-21 08:10:02 Perovskite solar cell flexible interface engineering non-radiative recombination quasi-Fermi level splitting 50 Energy Materials 100 Materials; 201 Electronics / Semiconductor / TCOs 206 Energy conversion / transport / storage / recovery 209 Solar cell / Photovoltaics 212 Surface and interfaces 306 Thin film / Coatings