Black phosphorus quantum dots in inorganic perovskite thin films for efficient photovoltaic application.

Gong, Xiu; Guan, Li; Li, Qingwei; Li, Yan; Zhang, Tao; Pan, Han; Sun, Qiang; Shen, Yan et al. · Sci Adv · 2020

basic_science · Level V

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Abstract

Black phosphorus quantum dots (BPQDs) are proposed as effective seed-like sites to modulate the nucleation and growth of CsPbI<sub>2</sub>Br perovskite crystalline thin layers, allowing an enhanced crystallization and remarkable morphological improvement. We reveal that the lone-pair electrons of BPQDs can induce strong binding between molecules of the CsPbI<sub>2</sub>Br precursor solution and phosphorus atoms stemming from the concomitant reduction in coulombic repulsion. The four-phase transition during the annealing process yields an α-phase CsPbI<sub>2</sub>Br stabilized by BPQDs. The BPQDS/CsPbI<sub>2</sub>Br core-shell structure concomitantly reinforces a stable CsPbI<sub>2</sub>Br crystallite and suppresses the oxidation of BPQDs. Consequently, a power conversion efficiency of 15.47% can be achieved for 0.7 wt % BPQDs embedded in CsPbI<sub>2</sub>Br film-based devices, with an enhanced cell stability, under ambient conditions. Our finding is a decisive step in the exploration of crystallization and phase stability that can lead to the realization of efficient and stable inorganic perovskite solar cells.