隨著科技日新月異，記憶體的需求也日漸龐大，其中電晶體型記憶體因相較於傳統電阻或電容式記憶體，具有讀取不易被中斷、多位元存儲等優點，而被廣泛討論。電晶體型記憶體是於一般電晶體中夾入一層可儲存電荷的駐極體層，我們將可透過控制這個電荷儲存層的高低導電態，來使其達到儲存電荷的目的。
在大部分文獻研究中，電晶體型記憶體資料的寫入與抹除方式不外乎是透過在閘極給予電壓，使得電荷束縛、被寫入於電荷儲存層中；若再給予反向電壓，則可再次注入異性電荷，使資料被抹除。但這樣的操作方式對於寫入與抹除程序來講，都各需要給予一次電壓，就能源層面來說勢必相當耗能，因此近年來有部分科學家開始著手研究「光驅動記憶體」，透過照光的方式來讓資料寫入記憶體的電荷儲存層中，但在這些研究中，被寫入後的裝置仍僅能透過給予電壓的方式將資料抹去。
在本研究中，我們將探討一種新型態的「光致還原記憶體」，這種電晶體型記憶體是先透過給予閘極偏壓將電荷注入具共軛結構的高分子電荷儲存層中，接著進行照射紫外光的動作，使駐極體分子內產生游離的正負激子，進而將先前束縛在內的電荷中和，回到初始狀態，達到「還原」裝置的效果。
我們先以聚芴當做駐極體，做為這類共軛高分子材料的代表，接著使用其單體與衍生物等材料做為佐證，證實了這樣的光還原現象確實導因於電荷儲存層對光的吸收。此外，在耐久性測試中，我們交錯進行注入電荷與照光的程序後記錄高低電壓，發現高達15次的迴圈後，裝置仍具有103以上的高開關電流比，實為一個可信的光記錄器。
最後，我們也試著在聚芴裝置照射各種波長的可見光，發現所有可見光皆可誘導光還原的發生，且還原速度與最終還原程度隨著光的能量(頻率)增加而上升，因此這樣的結果可應用於光色感測器，我們可以照射各種色光於預先被注入電荷的裝置上，藉由照光後的還原程度即可辨別其接收到的色光，如此的現象具有相當的潛力，在未來可望將這類型的記憶體應用於人工智慧當中，成為一個可靠的辨色元件。

As technology improves every day, there are more and more demands in memories. Among all the types of memories, transistor type memories have attracted lots of research interest since its advantages of non-destructive reading and multibit storage compared to conventional capacitance- and resistor- type memories. Transistor memory is a typical transistor integrated with an electret layer where the charges can be stored. We can modulate its high- and low-conducting states to make a transistor memory store charges.
In most of the studies, the way to write or erase data in memory is nothing more than electrically exerting a gate voltage to make charges trapped and written in the charge storage layer. If an opposite gate voltage is given, the counter-charges will be injected, making the data erased. However, the only way to exert biases for these processes is by electricity, which leads to high-energy consumption. As a consequence, there are recently some studies in “photo-programmed memories”, in which the charges will be stored in the charge storage layer after the device is illuminated. Nevertheless, the written device still needs to be erased by the electrical process in these researches.
In this study, we’re going to explore a new design, which is known as “photo-induced recovery memory”. In this kind of transistor memories, we injected charges into the charge storage layers composed of conjugated polymers, followed by the use of ultraviolet light to illuminate the device and prompting the generation of delocalized excitons. These excitons will then neutralize with the trapped charges and make the device back to the initial state.
We used polyfluorene as a representative of conjugated polymers to be the material for the charge storage layer and took its monomer and derivative as an evidence to prove that the recovery phenomenon is due to the absorption of light in the electret layer. Besides, we repetitively did the charge injections and illumination processes to conduct the endurance test, finding that the device can be reversibly switched without any obvious current decay after continuous 15-cycle measurements, which meets the standard of a photo-recorder.
Eventually, we tried to illuminate the device with visible lights. We found that visible lights with all wavelengths can recover the device. The recovery rate and extent become higher with the increase of light energy (frequency). This result can be used in light color sensors, where we can distinguish the received color by calculating the recovery extent after the illumination of different lights on a pre-programmed device. We hope this promising memory device can be used in the AI field to act as a reliable color distinguisher.

[1] A. D. B. Crone, Y.-Y. Lin, R. W. Filas, Z. Bao, A. LaDuca, R. Sarpeshkar, H. E. Katz, W. Li, Nature 2000, 403, 521.
[2] S. T. Han, Y. Zhou, V. Roy, Adv. Mater. 2013, 25, 5425
[3] Y.-H. Chou, H.-C. Chang, C.-L. Liu, W.-C. Chen, Polym. Chem. 2015, 6, 341
[4] T. Leydecker, M. Herder, E. Pavlica, G. Bratina, S. Hecht, E. Orgiu, P. Samorì, Nat. Nanotechnol. 2016, 11, 769.
[5] Y. Guo, G. Yu, Y. Liu, Adv. Mater. 2010, 22, 4427.
[6] C. R. Newman, D. A. da Silva Filho, J.-L. Bre´das, P. C. Ewbank, K. R. Mann, Chem. Mater. 2004, 16, 4436.
[7] D. A. Neamen, Semiconductor Physics and Devices: Basic Principles, McGraw-Hill Higher Education, 1996.
[8] H. S. Jana Zaumseil, Chem. Rev. 2007, 107, 1296.
[9] C. D. Sheraw, L. Zhou, J. R. Huang, D. J. Gundlach, T. N. Jackson, M. G. Kane, I. G. Hill, M. S. Hammond, J. Campi, B. K. Greening, J. Francl, J. West, Appl. Phys. Lett. 2002, 80, 1088.
[10] W. L. Leong, N. Mathews, B. Tan, S. Vaidyanathan, F. Dötz, S. Mhaisalkar, J. Mater. Chem. 2011, 21, 5203.
[11] L. Zhen, W. Guan, L. Shang, M. Liu, G. Liu, J. Phys. D: Appl. Phys. 2008, 41, 135111.
[12] M. Egginger, S. Bauer, R. Schwödiauer, H. Neugebauer, N. S. Sariciftci, Monatsh. Chem. 2009, 140, 735.
[13] P. Heremans, G. H. Gelinck, R. Müller, K.-J. Baeg, D.-Y. Kim, Y.-Y. Noh, Chem. Mater. 2011, 23, 341.
[14] C. Ríos, M. Stegmaier, P. Hosseini, D. Wang, T. Scherer, C. D. Wright, H. Bhaskaran, W. H. P. Pernice, Nat. Photonics 2015, 9, 725.
[15] L. J. Zhen, L. W. Shang, M. Liu, D. Y. Tu, Z. Y. Ji, X. H. Liu, G. Liu, J. Liu, H. Wang, Appl. Phys. Lett. 2008, 93, 203302.
[16] L. Zhang, T. Wu, Y. Guo, Y. Zhao, X. Sun, Y. Wen, G. Yu, Y. Liu, Sci. Rep. 2013, 3, 1080.
[17] O. Lopez-Sanchez, D. Lembke, M. Kayci, A. Radenovic, A. Kis, Nat. Nanotechnol. 2013, 8, 497.
[18] M. Kim, H. Seong, S. Lee, H. Kwon, S. G. Im, H. Moon, S. Yoo, Sci. Rep. 2016, 6, 30536.
[19] C.-C. Shih, W.-Y. Lee, Y.-C. Chiu, H.-W. Hsu, H.-C. Chang, C.-L. Liu, W.-C. Chen, Sci. Rep. 2016, 6, 20129.
[20] C.-C. Shih, Y.-C. Chiu, W.-Y. Lee, J.-Y. Chen, W.-C. Chen, Adv. Funct. Mater. 2015, 25, 1511.
[21] C. C. Shih, W. Y. Lee, W. C. Chen, Mater. Horiz. 2016, 3, 294.
[22] J. Y. Chen, Y. C. Chiu, Y. T. Li, C. C. Chueh, W. C. Chen, Adv. Mater. 2017, 29, 1702217
[23] M. Yi, M. Xie, Y. Shao, W. Li, H. Ling, L. Xie, T. Yang, Q. Fan, J. Zhu, W. Huang, J. Mater. Chem. C 2015, 3, 5220
[24] M.-Y. Chiu, C.-C. Chen, J.-T. Sheu, K.-H. Wei, Org. Electron. 2009, 10, 769
[25] X. Gao, C.-H. Liu, X.-J. She, Q.-L. Li, J. Liu, S.-D. Wang, Org. Electron. 2014, 15, 2486
[26] S.-W. Cheng, T. Han, T.-Y. Huang, Y.-H. Chang Chien, C.-L. Liu, B. Z. Tang, G.-S. Liou, ACS Appl. Mater. Interfaces 2018
[27] Y. Guo, C. a. Di, S. Ye, X. Sun, J. Zheng, Y. Wen, W. Wu, G. Yu, Y. Liu, Adv. Mater. 2009, 21, 1954.
[28] M. Redecker, D. D. C. Bradley, M. Inbasekaran, W. W. Wu and E. P. Woo, Adv. Mater., 1999, 11, 241.
[29] E. Ravindran and N. Somanathan, J. Mater. Chem. C, 5(19), 4763-4774, 2017.
[30] Y.-C. Chiu, C.-C. Shih, W.-C. Chen, J. Mater. Chem. C 2015, 3, 551.
[31] Y. C. Chiu, T. Y. Chen, C. C. Chueh, H. Y. Chang, a Kenji Sugiyama, Y. J. Sheng, Akira Hiraoc and W. C. Chen, J. Mater. Chem. C, 2014, 2, 1436–1446
[32] H. Yang, S. H. Kim, S. Y. Yang, L. Yang and C. E. Park, Adv. Mater., 2007, 19, 2868.
[33] H. L. Cheng, Y. S. Mai, W. Y. Chou, L. R. Chang and X. W. Liang, Adv. Funct. Mater., 2007, 17, 3639.
[34] Y. J. Jeong, D.-J. Yun, S. H. Noh, C. E. Park, J. Jang, ACS nano 2018, 12, 7701.
[35] Y. C. Chiu, I. Otsuka, S. Halila, R. Borsali and W. C. Chen, Adv. Funct. Mater., 2014, 24, 4240.
[36] W. C. Wu, C. L. Liu and W. C. Chen, Polymer, 2006, 47, 527.
[37] O. Ostroverkhova, Chem. Rev. 2016, 116, 13279.
[38] Y. Zhai, J.-Q. Yang, Y. Zhou, J.-Y. Mao, Y. Ren, V. A. Roy, S.-T. Han, Mater. Horiz. 2018, 5, 641.
[39] K. H. Park, W. Kim, J. Yang, D. Kim, Chem. Soc. Rev. 2018, 47, 4279.
[40] Y. C. Chiu, T. Y. Chen, Yougen Chen, Toshifumi Satoh, Toyoji Kakuchi, W. C. Chen, ACS Appl. Mater. Interfaces 2014, 6, 12780−12788
[41] Ramar, Alagar, Ramiah, Saraswathi, J. Mater. Sci. 50(10), 3740–3749. (2015)
[42] Morgado, J, H. Friend, R, Cacialli, Franco., Applied Physics Letters. 80. 2436-2438 (2002)
[43] T. D. Tsai , J. W. Chang , T. C. Wen , and T. F. Guo, Adv. Funct. Mater. 2013, 23(34), 4206-4214.
[44] Chaoyi Ban, Xiangjing Wang, Zhe Zhou, Huiwu Mao, Shuai Cheng, Zepu Zhang, Zhengdong Liu, Hai Li, Juqing Liu & Wei Huang, Scientific Reportsvolume 9, Article number: 10337 (2019)
[45] J.-W. van der Horst, P.A. Bobbert, W.F. Pasveer, M.A.J. Michels, G. Brocks, P.J. Kelly, Computer Physics Communications 147 (2002) 331–334
[46] Eric Moore, Benjamin Gherman, and David Yaron, J. Chem. Phys., Vol. 106, No. 10, 8 March 1997