Barrier Designs in Perovskite Solar Cells for Long‐Term Stability

Abstract

Perovskite solar cells (PSCs) have attracted much attention in the past decade and their power conversion efficiency has been rapidly increasing to 25.2%, which is comparable with commercialized solar cells. Currently, the long‐term stability of PSCs remains as a major bottleneck impeding their future commercial applications. Beyond strengthening the perovskite layer itself and developing robust external device encapsulation/packaging technology, integration of effective barriers into PSCs has been recognized to be of equal importance to improve the whole device’s long‐term stability. These barriers can not only shield the critical perovskite layer and other functional layers from external detrimental factors such as heat, light, and H2O/O2, but also prevent the undesired ion/molecular diffusion/volatilization from perovskite. In addition, some delicate barrier designs can simultaneously improve the efficiency and stability. In this review article, the research progress on barrier designs in PSCs for improving their long‐term stability is reviewed in terms of the barrier functions, locations in PSCs, and material characteristics. Regarding specific barriers, their preparation methods, chemical/photoelectronic/mechanical properties, and their role in device stability, are further discussed. On the basis of these accumulative efforts, predictions for the further development of effective barriers in PSCs are provided at the end of this review.

Slot-die coating large-area formamidinium-cesium perovskite film for efficient and stable parallel solar module

“…In combination of Bi and Al 2 O 3 barriers, the as-fabricated PSMs could withstand water immersing for several minutes without notable color change compared with the module without ALD Al 2 O 3 thin-film encapsulation (movie S5), which visually proves the barriers’ nonpermeability. It is being revealed that the integration of a nonpermeable barrier in PSCs is important for the long-term stability, which can affect the equilibrium of perovskite decomposition reaction from the perspective of thermodynamics ( 3 , 54 , 55 ). (iii) The parallel module design avoids the direct contact of metal electrode/grid with perovskite and allows an adequate space between the grids or electrodes and the perovskite layer.…”

Excellent Intrinsic Long‐Term Thermal Stability of Co‐Evaporated MAPbI3 Solar Cells at 85 °C

“…The device architectures, the selection of the perovskite compositions, [2][3][4] passivation strategies, [5][6][7][8] and the preparation procedures able to minimize ion migration [9,10] are crucial to guarantee the long-term stability of the PSCs. [11][12][13][14][15][16][17] Moreover, if the moisture resistance can be improved with proper encapsulation strategies, [18][19][20][21][22][23][24] the temperature stability instead, which is related to both perovskite intrinsic properties and the charge extraction interlayers in the PSCs, is still considered as the Achilles heels for the development of this technology.…”

A Review on Encapsulation Technology from Organic Light Emitting Diodes to Organic and Perovskite Solar Cells

“…The instability of PSCs mainly originates from the degradation of perovskite layer and/or other functional layers under external stressors such as oxygen, moisture, heat, light, and electric bias, etc. [ 30 ] as shown in Figure . For example, the generally used mesoporous titanium dioxide (TiO 2 ) scaffold decreases the stability of PSCs under illumination by the UV‐induced photocatalysis.…”

“…Appropriate high‐barrier encapsulation technologies, materials, structures, and processes can further prolong the stability and life expectancy of devices, and provide sufficient durability to make optoelectronic devices more commercially attractive (Figure 1b). [ 26,28–30 ]…”