Homogeneous Grain Boundary Passivation in Wide‐Bandgap Perovskite Films Enables Fabrication of Monolithic Perovskite/Organic Tandem Solar Cells with over 21% Efficiency

Abstract

Monolithic perovskite/organic tandem solar cells have attracted increasing attention due to their potential of being highly efficient while compatible to facile solution fabrication processes. One of the limiting factors for improving the performance of perovskite/organic tandem cells is the lack of wide‐bandgap perovskites with suitable bandgap, film quality, and optoelectronic properties for front cells. In addition, the development of low‐bandgap organic bulk‐heterojunction (BHJ) rare cells with extended absorption in the infrared range is also critical for improving tandem cells. This work has carefully optimized mixed halide wide‐bandgap perovskite (MWP) films by introducing a small amount of formamidinium (FA+) cations into the basic composition of MA1.06PbI2Br(SCN)0.12, which provides an effective means to modulate the crystallization properties and phase stability of the films. At optimized conditions, the MA0.96FA0.1PbI2Br(SCN)0.12 forms high‐quality films with grain boundaries homogeneously passivated by PbI2, leading to a reduction in defect states and an enhancement in phase stability, enabling the fabrication of perovskite solar cells with a power conversion efficiency(PCE) of 17.4%. By further integrating the MWP front cell with an organic BHJ (PM6:CH1007) rare cell composed of a nonfullerene acceptor with absorption extended to 950 nm, a tandem cell with PCE over 21% is achieved.

A hybrid technique employed for efficiency improvement of tandem perovskite solar cell

“…The primary purpose of this multilayer design was to permit light to enter with low reflection along to trap in the active layer because of Au nano spheres. Xie et al 36 have illustrated optimized mixed halide wide-band gap perovskite (MWP) films by introducing a small amount of formamidinium (FA+) cations into basic composition. Hu et al 37 have explained two novel solution-processed fullerene derivatives explicitly indene-C60-propionic acid butyl ester and indene-C60-propionic acid hexyl ester (IPH), as the inter layers in NBG PSCs.…”

Dual Sub‐Cells Modification Enables High‐Efficiency n–i–p Type Monolithic Perovskite/Organic Tandem Solar Cells

“…Monolithic perovskite/organic tandem solar cells (POTSCs) are attracting much attention owing to their ability to overcome the Shockley-Queisser limit, their simple solution-processed fabrication method, and their compatibility with flexible devices. [1][2][3][4] However, it is challenging to produce high-efficiency POTSCs because of the complex device design and integration and the need to simultaneously optimize many interfaces within the POTSCs. The highest reported power conversion efficiency (PCE) for POTSCs is limited to 24.0%, [5] which is still lower than the record PCE (25.7%) for singlejunction perovskite solar cells at the current stage.…”

Phase-segregation free quasi-2D perovskite/organic tandem solar cells with low Voc loss and efficiency beyond 21%

“…Beneting from the intrinsic properties of perovskites, such as high absorption coefficient, low exciton binding energy, long exciton diffusion length and high charge carrier mobilities, the power conversion efficiency (PCE) of perovskite solar cells (PSCs) has reached up to 25.6% in a few years. [1][2][3][4][5][6][7][8][9][10][11][12] Perovskitebased tandem solar cells (TSCs), [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] such as perovskite/Si TSCs, perovskite/CIGS TSCs, perovskite/perovskite TSCs, and perovskite/organic TSCs, together with the integrated perovskite/bulk-heterojunction solar cells, 69,70 have also attracted intense interest recently for their potential to overcome the Shockley-Queisser limit, and exhibit impressive advances. Presently, perovskite/Si TSCs exhibit a champion PCE of over 32%, though perovskite/Si tandem devices are incompatible with a low-temperature, low-cost fabrication process.…”