High-quality CsPbIBr2 films with a much lower self-doping level are obtained by the use of a CsI-rich precursor, which enables the fabrication of an all-inorganic, carbon-based solar cell with a superior efficiency of 10.48%.
The inorganic perovskite has a better stability than the hybrid halide perovskite, and at the same time it has the potential to achieve an excellent photoelectric performance as the organic-inorganic hybrid halide perovskite. Thus, the pursuit of a low-cost and high-performance inorganic perovskite solar cell (PSC) is becoming the research hot point in the research field of perovskite devices. In setting out to build vacuum-free and carbon-based all-inorganic PSCs with the traits of simple fabrication and low cost, we propose the ones with a simplified vertical structure of FTO/CsPbIBr2/carbon upon interfacial modification with PEI species. In this structure, both the electron-transporting-layer and hole-transporting-layer are abandoned, and the noble metal is also replaced by the carbon paste. At the same time, FTO is modified by PEI, which brings dipoles to decrease the work function of FTO. Through our measurements, the carrier recombination has been partially suppressed, and the performance of champion PSCs has far exceeded the control devices without PEI modification, which yields a power conversion efficiency of 4.9% with an open circuit voltage of 0.9 V and a fill factor of 50.4%. Our work contributes significantly to give an available method to explore charge-transporting-layer-free, low-cost, and high-performance PSCs.
One of the urgent key points to realize the commercialization of perovskite solar cells (PSCs) with robust and excellent performance is the fabrication of high‐quality perovskite film. Nevertheless, a traditional thermal annealing (TA) technology is always necessary for a high crystallization perovskite film, and previous reports have suggested that TA could induce heterogeneous nucleation which is inconducive for the formation of smooth and uniform perovskite film, as well as time and cost consuming. Herein, an approach for the annealing‐free high‐quality perovskite film via the introduction of guanidinium iodine (GAI) is proposed. The organic molecule guanidinium (GA+) has a large ionic radius, and this could control the crystallizing rate of annealing‐free perovskite film. Ultimately, a perovskite film with larger grain size and lower defect density is acquired through doping 0.10 mol mL−1 GAI in the precursor solution. Moreover, the fabrication of the electron transfer layer and hole transfer layer is further realized at room temperature. Thus, all room temperature, annealing‐free high‐performance PSCs are demonstrated. Notably, a GAI‐doped device with an outstanding power conversion efficiency (PCE) of 19.25% is obtained, much higher than 16.78% of the pristine device.
Four-terminal tandem solar cells employing a perovskite top cell and crystalline silicon (Si) bottom cell offer a simpler pathway to surpass the efficiency limit of market-leading single-junction silicon solar cells. To obtain cost-effective top cells, it is crucial to develop transparent conductive electrodes with low parasitic absorption and manufacturing cost. The commonly used indium tin oxide (ITO) shows some drawbacks, like the increasing prices and high-energy magnetron sputtering process. Transparent metal electrodes are promising candidates owing to the simple evaporation process, facile process conditions, and high conductivity, and the cheaper silver (Ag) electrode with lower parasitic absorption than gold may be the better choice. In this work, efficient semitransparent perovskite solar cells (PSCs) were firstly developed by adopting the composite cathode of an ultrathin Ag electrode at its percolation threshold thickness (11 nm), a molybdenum oxide optical coupling layer, and a bathocuproine interfacial layer. The resulting power conversion efficiency (PCE) is 13.38% when the PSC is illuminated from the ITO side and the PCE is 8.34% from the Ag side, and no obvious current hysteresis can be observed. Furthermore, by stacking an industrial Si bottom cell (PCE = 14.2%) to build a four-terminal architecture, the overall PCEs of 17.03% (ITO side) and 11.60% (Ag side) can be obtained, which are 27% and 39% higher, respectively, than those of the perovskite top cell. Also, the PCE of the tandem cell has exceeded that of the reference Si solar cell by about 20%. This work provides an outlook to fabricate high-performance solar cells via the cost-effective pathway.
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