Enhancing inverted perovskite solar cell performance via buried modification for improved interface and stability

Abstract

Inverted perovskite solar cells (IPSCs) are reported to be the most promising type of devices for industrialization. Hole-transport materials based on organic self-assembled molecules (OSAM) play a key role in enabling efficient and stable IPSCs. However, incomplete coating of OSAM film and poor energy alignment with perovskite result in non-radiative recombination loss at the bottom interface and poor crystal quality of perovskite film. In this study, anode interface carrier extraction and perovskite film crystallization were improved by introducing a layer of 5- ((5-nitrothiazole-2-yl) thioyl)-1,3,4-thiadiazole-2-amine (5-1T2A) between OSAM/perovskite. The experimental results show that 5-1T2A can optimize the energy arrangement of OSAM and perovskite thin films, improve the contact between anode interfaces, promote carrier extraction, reduce interface recombination loss, promote the nucleation and growth of perovskite thin films, and greatly improve the performance of the device. The PCE of the optimal device was increased from 21.82% to 23.50%. The 5-1T2A based IPSC achieved an average PCE of 22.37%, an improvement of nearly 9% over devices without 5-1T2A (average PCE of 20.59%). The average open circuit voltage (VOC) is increased from 1.108 V to 1.130 V, and the stability is enhanced. The 5-1T2A device retains more than 50% of the average PCE after thermal aging at 504 h (85 oC, N2), while the device without 5-1T2A retains only 38% of the initial PCE after 168h. In addition, the 5-1T2A device retained 103% of the initial PCE value after 468h storage at N2 (25 oC), while the device without 5-1T2A had an average PCE of 91% of the initial value.