Visualizing and Suppressing Nonradiative Losses in High Open-Circuit Voltage n-i-p-Type CsPbI₃ Perovskite Solar Cells

Abstract

Cesium lead iodide (CsPbI 3 ) has attracted increasing attention for its photovoltaic applications, owing to its thermal stability and suitable band gap for tandem solar cells. However, the severe nonradiative recombination losses in CsPbI 3 -based perovskite solar cells generally restrict their open-circuit voltage (V OC ) to the range of 0.9 to 1.1 V. This work uniquely reports a method to visualize all defect-assisted recombination pathways with photoluminescence (PL) techniques. Visible and valuable insight into the reduction of defect densities on a micrometer scale was obtained by the bottom surface and bulk passivation with barium hydroxide and trioctylphosphine oxide. The dual effects successfully improve the V OC of the solar cell from 0.87 to 1.17 V. These results highlight the potential of hyperspectral PL imaging as a powerful tool to give guidance to further suppress the nonradiative V OC losses in all-inorganic perovskites.

Composition Engineering of All‐Inorganic Perovskite Film for Efficient and Operationally Stable Solar Cells

“…[2][3][4][5][6] The 10 years' developments have witnessed a huge advancement of PSCs, with certified power conversion efficiency phase) under ambient conditions at room temperature, hindering the long-term application. [13,14] Many efforts have been devoted to stabilizing the α-phase of CsPbI 3 for photovoltaic applications, such as crystallization engineering, [15] additive engineering, [16][17][18][19][20][21][22] interface engineering, [22][23][24][25][26] compositional optimization, [27][28][29][30] dimensional engineering, [31,32] and synthesis of nanocrystals. [33] However, the small Goldschmidt tolerance factor t (≈0.8) of CsPbI 3 is the root cause, leading to the unstable cubic lattice structure at room temperature.…”

Structural Properties and Stability of Inorganic CsPbI3 Perovskites

“…Inorganic materials with excellent thermal and photostability, like NaOH, KOH, and Ba(OH) 2 , can reduce the density of surface defects effectively and promote the band energy alignment. Meng et al introduced solution‐processed Ba(OH) 2 as a surface modifier at the SnO 2 /CsPbI 3 interface, remarkably enhanced V OC from 0.87 to 1.07 V. [ 37 ] Ye et al developed an inorganic shunt‐blocking layer lithium fluoride (LiF) between SnO 2 and inorganic perovskites, which shifts the conduction band of SnO 2 minimum from 4.3 to 4.01 eV and the corresponding CsPbI 3− x Br x PSC exhibits a PCE of 18.64% ( Figure a,b). [ 43 ] Li et al incorporated layer‐structure‐tunable 2D black phosphorous (BP) to enhance the exciton dissociation efficiency in inorganic perovskites.…”

“…In this regard, additive engineering, interface engineering, and charge transfer layer (CTL) modifications are commonly studied and optimized. [ 35–43 ]…”

“…In this regard, additive engineering, interface engineering, and charge transfer layer (CTL) modifications are commonly studied and optimized. [35][36][37][38][39][40][41][42][43] Herein, we mainly discuss the structural stability of ILHPs and the strategies to improve device efficiency and stability. First, the structural stability, crystal structure, electronic structure, and optical properties of CsPbI 3 are introduced.…”

Clean production and utilisation of hydrogen in molten salts

“…As an extension of opportunities outlined in the previous section, photovoltaic (PV) technology can be utilised for the production of hydrogen, graphene, advanced alloys and hybrid structures in molten salts. Unlike the case of room temperature electrolysers that require more than 1.8 V, the voltage required to produce hydrogen in molten salts ($0.9 V) can be supplied by advanced perovskite single-solar cells with potentials in the range of 0.96-1.24 V. 109,110 This combination can lead to the highly efficient generation of hydrogen by solar energy. Fig.…”