Search

Abstract Organic-inorganic lead halide perovskite solar cells have garnered enormous interest in scientific communities due to comparable power conversion efficiencies and solution-processed fabrication techniques. Among them, carbon-based perovskite solar cells seem to be one of the most promising candidates for addressing the stability issue while suffering from inferior efficiency or high processing temperature. Herein, we introduce low-temperature processed Zn-doped SnO 2 (below 200 °C) as an effective electron transport layer in perovskite solar cells for the first time, and demonstrate a low-temperature carbon-based device with Cu-phthalocyanine as hole transport layer. We find that Zn doping contributes to a more suitable energy level alignment and an improved conductivity for SnO 2 films. As a result, the electron transfer and extraction are enhanced and the charge recombination is suppressed. In addition, devices with Zn-doped SnO 2 have a wider depletion region, leading to an enhanced photovoltaic performance. An optimal efficiency of 17.78% can be obtained after 2 mM Zn doping. Furthermore, these devices, introducing highly stable and hydrophobic Cu-phthalocyanine and carbon, maintain almost 100% of their initial efficiencies over 1200 h in ambient air. Our study paves the way for developing highly efficient and flexible carbon-based perovskite solar cells. Graphical abstract 17.78% efficient low-temperature carbon-based planar perovskite solar cell using Zn-doped SnO 2 electron transport layer is demonstrated. Zn doping contributes to a more favorable energy level alignment, an improved conductivity and a wider depletion region, resulting in an enhanced performance. The low-temperature and solution process realize flexible perovskite solar cells. Unlabelled Image Highlights • A high efficiency of 17.78% is achieved among carbon-based perovskite solar cells. • The whole process is conducted at low temperature (below 200 °C), enabling the fabrication of flexible devices. • The low-temperature processed Zn doped SnO 2 is introduced as an electron transporting layer in perovskite solar cells. • Excellent stability is obtained by utilizing CuPc and Carbon as hole transporting layer and electrode. [ABSTRACT FROM AUTHOR]

The solution processable electron extraction layer (EEL) is crucial for polymer solar cells (PSCs). Here, we investigated titanium (diisopropoxide) bis(2,4-pentanedionate) (TIPD) as an EEL and fabricated inverted PSCs with a blend of poly(3-hexylthiophene) (P3HT) and indene-C60 bisadduct (ICBA) acting as the photoactive layer, with a structure of ITO/TIPD/P3HT:ICBA/MoO 3 /Ag. After thermal annealing treatment at 150 °C for 15 min, the PSC performances increased from 3.85% to 6.84% and they achieve stable power conversion efficiency ( PCE ), with a similar PCE compared with TiO 2 as an EEL by the vacuum evaporated method. Fourier transform infrared spectroscopy (FTIR) and ultraviolet photoelectron spectroscopy (UPS) confirmed that the TIPD decomposed and formed the Ti O bond, and the energy level of the lowest unoccupied molecular orbital and the highest occupied molecular orbital increased. The space charge limited current (SCLC) measurements further confirmed the improvement in electron collection and the transport ability using TIPD as the EEL and thermal annealing. [ABSTRACT FROM AUTHOR]

Enhancing the optical, morphological and electronic properties of the solution-processed CsPbIBr 2 films by lithium doping for efficient carbon-based perovskite solar cells is demonstrated. The champion PCE of the CsPbIBr 2 cells is boosted from 7.41% to 9.25%, showing an increase by 24.8%. • A novel Li doping method is developed to enhance the morphological and electronic properties of the CsPbIBr 2 films. • The champion PCE of the carbon-based CsPbIBr 2 PSCs is boosted from 7.41% to 9.25% by 4% Li-doping. • Excellent moisture and thermal stabilities are obtained for the as-fabricated device. CsPbIBr 2 perovskite exhibits the most balanced bandgap and durability features among all the inorganic perovskites, showing great potential in the photoelectric field. Nevertheless, the poor film quality of the traditionally spin-coated CsPbIBr 2 restricts the further improvement of the device performance. Here, we develop a novel lithium (Li) doping strategy to promote the optical, morphological and electronic properties of the solution-processed CsPbIBr 2 perovskites. Upon incorporating Li+ ions into CsPbIBr 2 lattice, highly crystallized and well-oriented CsPbIBr 2 crystals are obtained. The as-prepared Li-doped CsPbIBr 2 exhibits a higher film coverage over the substrate with larger grains and less grain boundaries compared to the none-doped counterparts. The trap-state densities in the CsPbIBr 2 film are also effectively alleviated while the carrier lifetimes are elongated by Li doping, contributing to a lower energy loss and a higher charge collection efficiency. The optimized Li-doped perovskite solar cells (PSCs) demonstrate an excellent champion power conversion efficiency (PCE) of 9.25%, much higher than that of the none-doped devices (7.41%). Furthermore, the unencapsulated devices present a superior air and thermal stability under the protection of the hydrophobic CuPc layer and carbon electrode. Our work provides a new opportunity to fabricate cost-effective and highly efficient CsPbIBr 2 PSCs in a facile way. [ABSTRACT FROM AUTHOR]