Two-dimensional (2D) organic-inorganic halide perovskites have gained considerable attention in the past few years because they possess greatly enhanced environmental stability compared with the traditional three-dimensional counterparts and exhibit versatile and tunable optoelectronic properties. However, the insulating organic spacer may impede the smooth transport of charge carriers, leading to poor device performance. In this work, we demonstrated that a self-assembled monolayer (SAM) of poly [3-(6-carboxyhexyl)thiophene-2,5-diyl] (PHTCA) can be used as promising hole-transporting layer to fabricate high-performance quasi-2D perovskite solar cells (PSCs). The more coil-loke structure of PHTCA backbone effectively down-shifted the HMOM level, which is beneficial to boosting the open-circuit voltage (V_oc). The synergy effect of surface dipoles created by the anchored carboxylic acids and reduced surface defects facilitated the growth of PEA₂MA₄Pb₅I₁₆ perovskite into high-quality crystals with preferred orientation normal to the substrate. Consequently, the thus-prepared PSC exhibited a champion power conversion efficiency (PCE) of 17.74 % with a high V_OC of 1.24 V, which is only ~7% lower than the Shockley-Queisser limit of this perovskite. Very importantly, the device based on the self-assembled PHTCA retained 90% of its initial PCE after being stored at RH=70% for 1,500 hours and maintained 92% of the original PCE after being thermally aged at 95^oC for 3,300 hours. Our work paves the road for fabricating high-performance quasi-2D PCSs with excellent production yield.

<i>J</i>-<i>V</i> curves of quasi-2D perovskite solar cells under various light intensity.

J-V curves of quasi-2D perovskite solar cells under various light intensity.

Hsinhan Tsai

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