>Magister Scientiae - MSc / Environmentally friendly photovoltaic devices make use of solar radiation as the energy source to generate electricity. Organic solar cells (OSCs) have been making headway in the last decade due to their cost-effectiveness and potential application in flexible devices. One of the disadvantages of OSCs is the short lifetime of the charge carriers, where the various interfaces that are present in the material play a significant role. In the inverted organic solar cell (IOSC), electrons are injected into the transparent conducting oxide, whereby the electrode alignment is reversed compared to the conventional structure. Nanosized zinc oxide (ZnO) thin-films with nanoridges/ripples embedded on the surface of the thin-film can be used as an electron transport/hole-blocking layers in inverted organic solar cells to enhance light-capturing by the active layer of the solar cell.

Semiconductors with an additional intermediate band (IB) have the potential to greatly improve solar cell efficiency. Their theoretical efficiency limit is over 50% higher than that of standard semiconductor solar cells at full concentration. In practice however, their efficiencies are low compared to this detailed balance limit. Part of the reason is that it has not been possible to optimize IB device geometry because no device model has existed that could capture all the effects present in IB materials (e.g., charge transport inside the IB and self-consistent optics). In this thesis I introduce my new device model for intermediate band semiconductors called Simudo. The software uses the finite element method to solve the coupled Poisson/drift-diffusion (PDD) system of equations that describe the carrier dynamics inside semiconductor (IB or not) devices, along with optical propagation. I benchmark its accuracy on standard semiconductor problems against Synopsys Sentaurus, and I find that not only does it give valid results but in fact converges to the solution with a smaller number of mesh points by having quartic rather than merely quadratic solution convergence with respect to the number of mesh points. I also demonstrate Simudo's immediate usefulness by answering the question of whether IB mobility can compensate for mismatched optical absorption processes in different regions of the device. The device model work is preceded by three introductory chapters bringing the reader up to speed on semiconductor device physics and providing them with a primer on the finite element method. The coupled PDD equations are numerically challenging to solve, and the road to development of Simudo tried a number of formulations of the problem that were not successful. In the final chapter I discuss some of these formulations and why they did not succeed.

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京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第17911号 / エネ博第283号 / 新制||エネ||59(附属図書館) / 30731 / 京都大学大学院エネルギー科学研究科エネルギー基礎科学専攻 / (主査)教授 佐川 尚, 教授 八尾 健, 教授 石原 慶一 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第18291号 / 工博第3883号 / 新制||工||1596(附属図書館) / 31149 / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 伊藤 紳三郎, 教授 木村 俊作, 教授 辻井 敬亘 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第18381号 / エネ博第293号 / 新制||エネ||61(附属図書館) / 31239 / 京都大学大学院エネルギー科学研究科エネルギー基礎科学専攻 / (主査)教授 佐川 尚, 教授 八尾 健, 教授 萩原 理加 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19007号 / 工博第4049号 / 新制||工||1623(附属図書館) / 31958 / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 伊藤 紳三郎, 教授 赤木 和夫, 教授 辻井 敬亘 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第19829号 / エネ博第335号 / 新制||エネ||67(附属図書館) / 32865 / 京都大学大学院エネルギー科学研究科エネルギー応用科学専攻 / (主査)教授 松田 一成, 教授 佐川 尚, 教授 大垣 英明 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20406号 / 工博第4343号 / 新制||工||1673(附属図書館) / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 大北 英生, 教授 辻井 敬亘, 教授 竹中 幹人 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第20657号 / 理博第4322号 / 新制||理||1621(附属図書館) / 京都大学大学院理学研究科化学専攻 / (主査)教授 寺西 利治, 教授 島川 祐一, 教授 小野 輝男 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM