利用電性量測分析太陽電池缺陷影響及鐵電之電場加強效率改善

Abstract

本文的實驗分成三個部分。第一部分是研究MoSe2對銅銦鎵硒(CIGS)太陽電池電性的影響。首先我們以XRD、Van der Pauw法、反射光譜、以及SEM影像來探查MoSe2的存在。然後改變溫度環境，量測光電流以推算背電極的蕭基能障。因此，我們得知CIGS製程中產生的MoSe2可以最小化蕭基能障對太陽能電池的負面效應。

第二部分，利用導納能譜(admittance spectroscopy)量測，可以推算缺陷的活化能與缺陷的密度。由硒化溫度在450oC與550oC的CIGS太陽能電池顯示，不足的硒化溫度會使CIGS薄膜內存在過多的塊材缺陷，而降低太陽能電池的效率。當硒化溫度上升，塊材缺陷減少，因此我們量測到較高的效率與較低的缺陷活化能。

第三部分，嘗試製作結合鐵電材料鋯鈦酸鉛(PZT)的異質接面(HIT)太陽能電池。利用電子束蒸鍍將鐵電材料PZT蒸鍍至 HIT太陽能電池上，引入一個永久的內部電場，取代外加偏壓。第一次試製發現HIT太陽能電池的效率有顯著的提升。於是嘗試最佳化PZT薄膜的厚度，但是發現PZT並沒有產生極化電場，試製之HIT太陽能電池的效率只與電極有直接關係。The first part of this thesis is about the electrical impact of MoSe2 on CIGS thin-film solar cells. Samples were characterized by XRD, the van der Pauw method, reflectance, and visual inspection. Then Schottky barrier heights of cells were extracted from J–V–T measurements. Therefore, the formation of MoSe2 during the CIGS process should minimize the negative effect of Schottky barrier on solar-cell performances, especially with large Schottky barrier.

In the second part, CIGS solar cells in different selenization temperature were compared. The relationship between basic solar-cell parameters and carrier-trapping states is explored through current-voltage, and admittance spectroscopy (AS). CIGS solar cells with selenization temperature at 550oC have higher efficiency and lower defect activation energies than cells with lower selenization temperatures.

In final part, we attend to incorporate a ferroelectric polymer layer into HIT solar cells. The ferroelectric material PZT was deposited on HIT solar cells by electron beam Evaporator. The polarization electric field induced by PZT would reduce the recombination of electrons and holes in semiconductors, eliminate the need for an external bias. In the first try, we found the efficiency on HIT solar cells have improvement. Then we try to find the thick of PZT with best performance. But we didn’t find any polarization in HIT solar cell. The performance relate to the Al contact directly.