Vapor-assisted deposition of CsPbIBr2 films for highly efficient and stable carbon-based planar perovskite solar cells with superior Voc

• Published in: Electrochimica acta 2020-01, Vol.330, p.135266, Article 135266
• Main Authors: Liu, Xingyue, Li, Junjie, Liu, Zhiyong, Tan, Xianhua, Sun, Bo, Xi, Shuang, Shi, Tielin, Tang, Zirong, Liao, Guanglan
• Format: Article
• Language: English
• Subjects: Carbon; Crystal growth; Crystallization; CsPbIBr2; Deposition; Electromagnetic absorption; Energy conversion efficiency; Grain size; Harvesters; High Voc; Highly efficient and stable; Morphology; Motion pictures; Organic chemistry; Perovskite solar cell; Perovskites; Photovoltaic cells; Protective coatings; Solar cells; Spin coating; Substrates; Thickness; Vapor-assisted
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2019.135266

CsPbIBr2 perovskite, as a promising light harvester, possesses the most balanced bandgap and stability characters among all-inorganic perovskite materials. However, the poor quality of the traditionally one-step solution-processed CsPbIBr2 film always leads to a severe recombination loss and thus a low output potential difference (Voc). Herein, we demonstrate a novel vapor-assisted deposition strategy to construct high-quality CsPbIBr2 films for the first time, in which the crystallization kinetics of the CsPbIBr2 is more easily controllable than that of the one-step spin-coated one. The PbBr2 film acting as the template in the CsPbIBr2 crystal growth is firstly prepared via an antisolvent-washing technique and CsI is then vacuum evaporated onto the PbBr2 layer. By precisely tuning the thickness of the CsI film, highly phase-pure and crystallized CsPbIBr2 crystals are successfully obtained. The optimized CsPbIBr2 film also exhibits a homogeneous morphology and full coverage over the substrate with large grain sizes up to microscale and ultrahigh light absorption capability. The corresponding carbon-based CsPbIBr2 solar cells achieve a champion power conversion efficiency of 8.76% with a superior Voc of 1.289 V. The large-area (1 cm2) devices also deliver an efficiency of 6.78% with an impressive Voc of 1.336 V. Moreover, under the protection of the highly hydrophobic and chemically stable CuPc layer and carbon counter electrode, the unencapsulated devices present excellent moisture and thermal stabilities. Our work provides a new approach for the preparation of cost-effective, highly efficient and robust CsPbIBr2 photovoltaics. Vapor-assisted deposition of CsPbIBr2 films for highly efficient and stable carbon-based planar perovskite solar cells with superior Voc are demonstrated. A champion PCE of 8.76% with an superior Voc of 1.289 V as well as excellent moisture and thermal stabilities are achieved. [Display omitted] •A novel and facile vapor-assisted deposition method is developed to fabricate CsPbIBr2 perovskites for the first time.•Highly phase-purity and crystallized CsPbIBr2 films with large grain sizes are obtained.•A high PCE of 8.76% with a superior Voc of 1.289 V is achieved.•A PCE of 6.78% with an impressive Voc of 1.336 V is gained for the large-area (1 cm2) devices.•Excellent moisture and thermal stabilities are obtained for our devices.