The power conversion efficiency (PCE) of perovskite solar cells (PSCs) is predominantly limited by interfacial and bulk recombination losses in the electron transport layer (ETL). To address this, we introduce a rational molecular engineering strategy that integrates 4-aminopyridine-2,6-dicarboxylic acid (4-APDA) into hydrothermally derived TiO2 ETLs. As a bifunctional, cost-effective interfacial modifier, 4-APDA enables concurrent passivation of defects in three critical domains: the TiO2 bulk, its surface, and the TiO2/perovskite heterojunction—leading to pronounced improvements in charge extraction, transport, and collection. Mechanistically, the carboxylate groups chelate undercoordinated Ti4+ ions and compensate for oxygen vacancies, thereby eliminating deep-level trap states and increasing electron mobility. Simultaneously, the amino group coordinates strongly with undercoordinated Pb2+ ions at the perovskite surface and grain boundaries, guiding the crystallization of dense, highly oriented, and phase-pure CsPbI3-xBrx films. Consequently, the champion device fabricated with 3 mg/ml 4-APDA achieves a certified PCE of 12.49%, corresponding to an absolute enhancement of 3.36% relative to the control (9.13%). Importantly, operational stability is significantly enhanced—retaining >84% of its initial PCE after 35 days of continuous illumination under standard AM 1.5G conditions (100 mWcm-2). This work establishes a scalable, solution-processable, and industrially relevant paradigm for high-efficiency all-inorganic PSCs via targeted molecular interface design.

Genyang Li, Fanghui Zhang, Kaiyuan Gou. Highly Stable All-Inorganic Perovskite Solar Cells via Synergetic Passivation with 4-Aminopyridine-2, 6-Dicarboxylic Acid. Academic Journal of Materials & Chemistry (2026), Vol. 7, Issue 1: 50-58. https://doi.org/10.25236/AJMC.2026.070108.

[1] Kojima A, Teshima K, Shirai Y, et al. Organometal halide perovskites as visible-light sensitizers for photovoltaic cells[J]. Journal of the American Chemical Society, 2009, 131(17): 6050-6051.

[2] Min H, Lee D Y, Kim J, et al. Perovskite solar cells with 25.2% efficiency and superior operational stability[J]. Nature, 2021, 598(7881): 444-450.

[3] Tan H, Jain A, Voznyy O, et al. Efficient and stable solution-processed planar perovskite solar cells via contact passivation[J]. Science, 2017, 355(6326): 722-726.

[4] Chen C, et al. Recent advances in ionic liquid-modified TiO2 for perovskite solar cells[J]. Journal of Materials Chemistry A, 2023, 11(25): 13142-13165.

[5] Yoo J J, Seo G, Chua M R, et al. Efficient perovskite solar cells via improved carrier management[J]. Nature, 2021, 590(7847): 587-593.

[6] Bakr O M, Mohammed O F. Defect engineering in semiconductor perovskites[J]. Nature Reviews Materials, 2020, 5(3): 194-211.

[7] Wang R, Xue J, Wang K L, et al. Constructive molecular configurations for surface-defect passivation of perovskites[J]. Science, 2019, 366(6472): 1509-1513.

[8] Jiang Q, Zhao Y, Zhang X, et al. Surface passivation of perovskite solar cells with organic halides[J]. Nature Photonics, 2019, 13(7): 460-466.

[9] Jacobsson T J, Correa-Baena J P, Halvani Anaraki E, et al. Unreacted PbI2 as a double-edged sword for enhancing the performance of perovskite solar cells[J]. Journal of the American Chemical Society, 2016, 138(32): 10331-10343.

[10] Wu W, Han W, Deng Y, et al. Low-cost and easily prepared interface layer towards efficient and negligible hysteresis perovskite solar cells[J]. Journal of Colloid and Interface Science, 2022, 617: 745-751.

[11] You J, Meng L, Song T B, et al. Improved air stability of perovskite solar cells via solution-processed metal oxide transport layers[J]. Nature Nanotechnology, 2016, 11(1): 75-81.

[12] Jeon N J, Lee H G, Kim Y C, et al. Compositional engineering of perovskite materials for high-performance solar cells[J]. Nature, 2015, 517(7535): 476-480.

[13] Beal R E, Slotcavage D J, Leijtens T, et al. Cesium lead halide perovskites with improved stability for tandem solar cells[J]. The Journal of Physical Chemistry Letters, 2016, 7(5): 746-751.

[14] Jiang E, Ai Y, Yan J, et al. Phosphate-passivated SnO2 electron transport layer for high-performance perovskite solar cells[J]. ACS Applied Materials & Interfaces, 2019, 11(40): 36727-36734.

[15] Li T, Rui Y, Wang X, et al. Grain size and interface modification via cesium carbonate post-treatment for efficient SnO2-based planar perovskite solar cells[J]. ACS Applied Energy Materials, 2021, 4(7): 7002-7011.

[16] Jung E H, Chen B, Bertens K, et al. Bifunctional surface engineering on SnO2 reduces energy loss in perovskite solar cells[J]. ACS Energy Letters, 2020, 5(9): 2796-2801.