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Enhancing the Performance of Inverted Perovskite Solar Cells via Grain Boundary Passivation with Carbon Quantum Dots.

Research paper by Yuhui Y Ma, Heyi H Zhang, Yewei Y Zhang, Ruiyuan R Hu, Mao M Jiang, Rui R Zhang, Hao H Lv, Jingjing J Tian, Liang L Chu, Jian J Zhang, Qifan Q Xue, Hin-Lap HL Yip, Ruidong R Xia, Xing'ao X Li, Wei W Huang

Indexed on: 27 Dec '18Published on: 27 Dec '18Published in: ACS Applied Materials & Interfaces



Abstract

The non-radiative recombination, the main energy loss channel for open circuit voltage (Voc), is one of the crucial problems for achieving high power conversion efficiency (PCE) in inverted perovskite solar cells (PSCs). Usually, grain boundary passivation is considered as an effective way to reduce non-radiative recombination because the defects (uncoordinated ions) on grain boundaries are passivated. We added the hydroxyl and carbonyl functional groups contained carbon quantum dots (CQDs) into perovskite precursor solution to passivate the uncoordinated lead ions on grain boundaries. Higher photoluminescence intensity and longer carrier lifetime were demonstrated in the perovskite film with CQDs additive. This confirmed that the addition of CQDs can reduce non-radiative recombination by grain boundary passivation. Additionally, the introduction of CQDs could increase the thickness of perovskite film. Consequently, we achieved a champion device with PCE of 18.24%. The device with CQDs remained 73.4% of its initial PCE after aged for 48 hours under 80% humidity in the dark at room temperature. Our findings reveal the mechanisms of how CQDs passivate the grain boundaries of perovskite which can improve the efficiency and stability of perovskite solar cells.

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