Highly Efficient HTM-Free Tin Perovskite Solar Cells with Outstanding Stability Exceeding 10000 h

The bottleneck in the rapid development of tin-basedperovskitesolar cells (TPSCs) is the inherent chemical instability. Althoughthis is being addressed continuously, the device performance has notimproved further due to the use of PEDOT:PSS as the hole-transportmaterial (HTM), which has poor long-term stability. Herein we haveapplied commercial ITO nanoparticles over ITO glass substrates andaltered the surface chemistry of the ITO electrode via a simple two-stepthermal annealing, followed by a UV-ozone treatment. Thesesurface-modified ITO electrodes display promising interfacial characteristics,such as a suitable band alignment owing to significantly reduced surfacecarbon contamination, increased In-O bonding, and reduced oxygenvacancies, that enabled fabrication of an HTM-free TPSC device accordingto a two-step method. The fabricated device possessed an outstandingpower conversion efficiency (PCE) of 9.7%, along with a superior long-termstability by retaining over 90% of the initial PCE upon shelf storagein a glovebox for a period of over 10000 h. The application of ITOnanoparticles led to effective interfacial passivation, whose impactson the long-term durability were assessed using electrochemical impedancespectroscopy, time-resolved photoluminescence decay profiles, andfemtosecond transient absorption spectroscopy techniques.