The Study Of Inorganic Or Inorganic Organic Hybrid Thin Film Solar Cells

This study is about the properties of the CdS in CdS/CdTe thin film solar cells and the properties of perovskite materials in the planar heterojunction perovskite solar cells. The details of the research results are as follows:1. Conventional and inverted thin CdS/CdTe based solar cells are fabricated using thermal deposition techniques, and their performance under an external electric field is investigated. Results show that the performance of the developed solar cells can be changed both by positive and negative electric fields and then recover to its initial state after switching the external electric field off. Heat treatment experiments confirm the negligible impact of the temperature on the solar cell performance. Transient photocurrent experiments show that the carrier transfer efficiency is modulated directly by an external electric field. By taking into account the CdS nanodipole, the effect of an external electric field on the solar cell performance can be well explained. The results presented in this paper open the way towards the realization of solar cells through carrier separation by an electric field provided by the CdS nanodipoles rather than the junction.2. The planar heterojunction perovskite solar cells were fabricated by spin-coating method, which contained the hole and electron transport layer of PEDOT:PSS and PCBM, respectively. The maximum efficiency of 9% and the best open circuit voltage of 0.97 V were acquired. Besides, most open circuit voltages of the devices that fabricated in the same batches were higher than 0.9 V. On the condition of integration time 0.01s scan rate, some I-V curves of the perovskite solar cells show the outer-convex shape. This phenomenon can be eliminate gradually by decreasing scan rate or increasing the sweep delay to 100 ms, so we guessed that the outer-convex I-V curves is due to the effect of capacity in perovskite materials that can be charged and discharged at high scan rate. In addition, we found that the performance of planar heterojunction perovskite solar cells can be rapidly improved by a short continuous illumination. Furthermore, the continuous illumination method can gradually eliminate the outer-convex of I-V curves. Combining above experimental results with the literature researches, we believe that the light can drive the positive and negative charges that contain in perovskite materials under the rapid measurement processes. At the same time continuous illumination can change the doping type of the perovskite materials and obtain the best distribution of PN doping for separating the photon-generated carriers.