Constructing an Interfacial Gradient Heterostructure Enables Efficient CsPbI₃ Perovskite Solar Cells and Printed Minimodules

Abstract

Severe nonradiative recombination originating from interfacial defects together with the pervasive energy level mismatch at the interface remarkably limits the performance of CsPbI3 perovskite solar cells (PSCs). These issues need to be addressed urgently for high‐performance cells and their applications. Herein, an interfacial gradient heterostructure based on low‐temperature post‐treatment of quaternary bromide salts for efficient CsPbI3 PSCs with an impressive efficiency of 21.31% and an extraordinary fill factor of 0.854 is demonstrated. Further investigation reveals that Br− ions diffuse into the perovskite films to heal undercoordinated Pb2+ and inhibit Pb cluster formation, thus suppressing nonradiative recombination in CsPbI3. Meanwhile, a more compatible interfacial energy level alignment resulting from Br− gradient distribution and organic cations surface termination is also achieved, hence promoting charge separation and collection. Consequently, the printed small‐size cell with an efficiency of 20.28% and 12 cm2 printed CsPbI3 minimodules with a record efficiency of 16.60% are also demonstrated. Moreover, the unencapsulated CsPbI3 films and devices exhibit superior stability.

Solution fabrication methods and optimization strategies of CsPbBr3 perovskite solar cells

“…18 Unfortunately, CsPbI 3 perovskite normally exists in a yellow non-perovskite phase at room temperature, unsuitable as a perovskite absorber; it becomes a black cubic perovskite phase (bandgap of ∼1.73 eV) only after being heated above ∼310 °C, which limits its photovoltaic applications. 19…”

Small molecule-incorporated SnO2 layer for efficient perovskite solar cells

“…5 However, the non-radiative recombination caused by PSC interface defects hinders any further improvement in the PCE and stability. 6–9 The interface designs of the electron transport layer (ETL)/perovskite are important to realize highly efficient and stable PSCs. 10–14…”

“…5 However, the non-radiative recombination caused by PSC interface defects hinders any further improvement in the PCE and stability. [6][7][8][9] The interface designs of the electron transport layer (ETL)/perovskite are important to realize highly efficient and stable PSCs. [10][11][12][13][14] Currently, various modifiers are used to reduce defects in the ETL/perovskite interface, [15][16][17] such as Lewis acid-based compounds 18 and cations, 19 and research has been conducted to improve their interfacial properties.…”

Efficient inverted CsPbI3inorganic perovskite solar cells achieved by facile surface treatment with ethanolamine

“…Various strategies including crystallization regulation, 1,5 additive engineering, 6,7 and deposition technology, 8,9 have been developed to vastly boost the device efficiency and stability of CsPbI 3 PSCs. Although the maximum PCE has exceeded 20%, 10–13 almost all of the reported highly efficient CspbI 3 PSCs are based on the normal structure devices and usually involve the use of photocatalytic active TiO 2 and hygroscopic dopants, which has been identified as one of the major origins for PSC degradation. 14–16 In contrast, the inverted CspbI 3 PSCs can refrain from the use of undesirable transport layers and also possess a compatible manufacturing process with the tandem architecture.…”