An organic semiconductor obtained with a low-temperature process for light-addressable potentiometric sensors

• Published in: Sensors and actuators. B, Chemical Vol. 381; p. 133449
• Main Authors: Yang, Chia-Ming, Yang, Yu-Cheng, Jiang, Bing-Huang, Yen, Jiun-Han, Su, Xuan-Ming, Chen, Chih-Ping
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.04.2023
• Subjects: LAPS; Organic semiconductor; PC71BM; pH sensitivity; PTB7-Th; ZnO; ZnO; LAPS; PC71BM; pH sensitivity; PTB7-Th; Organic semiconductor
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2023.133449

In this study, the first trial of donor and acceptor bulk heterojunctions (BHJs) is proposed for light-addressable potentiometric sensors (LAPSs) due to organic conjugated molecules with the advantages of energy level/band gap modification and high absorption of visible light. The benzodithiophene-based polymer PTB7-Th and fullerene PC71BM are selected for integration with an Al2O3 sensing membrane using atomic layer deposition at temperatures lower than 100 ℃ for pH sensing LAPS. In the stability performance, the hysteresis width of the best condition with a mixing weight ratio of PC71BM to PTB7-Th of 1.5 is 4.4 mV, which is inferior to that of the conventional inorganic semiconductor-based LAPSs. By means of an additional spin-coated zinc oxide (ZnO) layer, the signal-to-noise ratio of the photocurrent of this fabricated LAPS can be maintained at 3.2 after 170 min of measurement with an acceptable sensitivity, linearity, drift coefficient and hysteresis of 50.2 mV/pH, 99.9%, − 3.1 mV/h and 1.4 mV, respectively. With the proper adjustment of illumination with low power and large spots, chemical imaging with a scanning step of 25 µm can be conducted to indicate the feasibility of this low-temperature process developed for spin-coated organic semiconductor-based LAPSs. •Organic semiconductor is first used in light-addressable potentiometric sensors.•Low-temperature processes including spin coating and ALD are developed.•A ZnO layer before organic semiconductor is used to improve the sensing stability.•pH sensing and 2D chemical imaging are both achieved in organic LAPS.