The measurement of photocurrent in conjugated polymer MEH-PPV

• Main Authors: Chao-Yi Tsai, 蔡朝儀
• Other Authors: Pei-Hsi Tsao
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/16162061994974025693

碩士 === 國立臺灣大學 === 物理學研究所 === 88 === There are two main purposes in this research. One is to establish the system of measurement in photocurrent. The other one is to measure the photocurrent’s spectra of conjugated polymer MEH-PPV in forward, reversed bias and short-circuit with different temperatures, in order to realize the mechanism which influences photocurrent. Is it exactly tended to the general theory of semiconductor’s band model or exciton model? According to our measurements, we find that it has much accordance in forward-circuit photocurrent’s spectrum with its absorption spectrum at room temperature. We also find that the first state the peak around 500nm has a red shift inits reversed bias-circuit photocurrent’s spectrum. In addition,in low temperature, we observe that no matter in forward or reversed bias circuit that all the first state’s photocurrent has evidently the same situation to be quenched. As a result, we conjecture that the result of mechanism is from the carriers’ different processes by light, but is not caused by the different proceeding transportation. Besides, when decreasing the temperature, the reduce of the photocurrent’s spectrum in the first state and the second state (the peak around 340nm) is inconsistent. And from experiment of changing temperatures, we find that the first state has the tendency of red-shift, except in reversed bias. However, on the contrary, the second state has a slightly blue shift. As a result, we infer that two states are from different carriers’ mechanism. Besides, in an analysis of photocurrent with the temperature, in 500nm, above 200K, no matter 0V, 1.0V or —2.0V we can discover that the relationship with photocurrent and the temperature has reciprocal linear relation. But when below 200K, the photocurrent doesn’t have strong relation with temperature. Also in 340nm,the relationship with photocurrent and temperature is neither reciprocal form nor exponential form when with bias. But in the short-circuit, it has the relation of exponential form.