Effect of Hole Transport Materials and Their Dopants on the Stability and Recoverability of Perovskite Solar Cells on Very Thin Substrates after 7 MeV Proton Irradiation

Abstract The drastic reduction in launch and manufacturing costs of space hardware has facilitated the emergence of "commercial" space. Radiation‐hard organometal halide perovskite solar cells (PSCs) with low‐cost and high‐efficiency potentials are promising for space applications.High‐efficiency PSCs are tested with different hole transport materials (HTMs) and dopants on 175µm sapphire substrates under 7MeV‐proton‐irradiation‐tests at accumulated fluences of 10¹¹, 10¹², and 10¹³ protons cm⁻². While all cells retain >90% of their initial power conversion efficiencies (PCEs) after 10¹¹ protons cm⁻² irradiation, PSCs that have tris(pentafluorophenyl)borane (TPFB) as the HTM dopant and poly[bis(4‐phenyl)(2,5,6‐trimethylphenyl) amine (PTAA) or PTAA:C8BTBT (C8BTBT = 2,7‐Dioctyl[1]benzothieno[3,2‐b][1]benzothiophene) as the HTM are more tolerant to higher‐fluence radiation than their counterparts with the lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) dopant and the 2,2′,7,7′‐Tetrakis[N,N‐di(4‐methoxyphenyl)amino]‐9,9′‐spirobifluorene (Spiro‐OMeTAD) HTM. Radiation induces fluorine diffusion from the LiTFSI dopant toward the perovskite absorber (confirmed by depth‐resolved X‐ray photoelectron spectroscopy) introducing defects. Radiation‐induced defects in cells with the TPFB dopant instead are different and can be “annealed out” by thermal vacuum resulting in PCE recovery. This is the first report using thermal admittance spectroscopy and deep‐level transient spectroscopy for defect analyses on proton‐irradiated and thermal‐vacuum‐recovered PSCs. The insights generated are expected to contribute to efforts in developing low‐cost light‐weight solar cells for space applications.