發(fā)布時(shí)間：2018-01-05 08:12

  本文關(guān)鍵詞：鈣鈦礦太陽能電池電子和離子電荷動(dòng)力學(xué)研究　出處：《中國科學(xué)院大學(xué)(中國科學(xué)院物理研究所)》2017年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 鈣鈦礦電池 異質(zhì)結(jié) 界面調(diào)控 電荷輸運(yùn) 瞬態(tài)測(cè)量

【摘要】：太陽能光伏技術(shù)是解決目前日益嚴(yán)重的能源與環(huán)境問題的重要手段之一,對(duì)于優(yōu)化能源結(jié)構(gòu)、改善環(huán)境和促進(jìn)可持續(xù)發(fā)展意義重大。發(fā)展更低成本、更高效率的太陽能電池一直是光伏研究的熱點(diǎn)。太陽能電池經(jīng)歷了第一代晶硅、砷化鎵到第二代硫系異質(zhì)結(jié)薄膜,直至目前第三代基于新材料和新工作機(jī)理的新型薄膜太陽能電池。鈣鈦礦電池正是近幾年被開發(fā)并得到迅速發(fā)展的一種新型光伏器件。液相沉積的鈣鈦礦(比如甲胺鉛碘(CH_3NH_3PbI_3)、甲脒鉛碘(CH(NH_2)_2PbI_3)及其合金化合物)多晶薄膜具有高的光吸收系數(shù)(105 cm-1),低的缺陷態(tài)濃度(1016 cm-3)和較長的載流子擴(kuò)散長度。基于這些優(yōu)異的半導(dǎo)體性能、高質(zhì)量薄膜沉積以及器件結(jié)構(gòu)和界面調(diào)控的實(shí)現(xiàn),小面積鈣鈦礦電池的光電轉(zhuǎn)化效率在短短數(shù)年內(nèi)被提高到22.1%,與商業(yè)化的多晶硅、銅銦鎵硒和碲化鎘電池相當(dāng)。然而,鈣鈦礦電池依然面臨穩(wěn)定性及可工業(yè)化大面積生產(chǎn)等諸多挑戰(zhàn)。同時(shí),在鈣鈦礦電池的發(fā)展過程中,對(duì)于其材料和器件的本質(zhì)屬性(激子VS非激子、敏化VS異質(zhì)結(jié))和反常的光電遲滯行為及其物理機(jī)制方面均存在爭議�；诖�,我們從電池的電子和離子電荷動(dòng)力學(xué)的角度對(duì)該器件的基本物理性質(zhì)進(jìn)行和研究,并通過電荷動(dòng)力學(xué)調(diào)控等手段獲得了高的器件性能,取得了如下研究成果:(1)通過二次重結(jié)晶的手段制備了致密平滑的PbI_2薄膜,并最終獲得了高質(zhì)量的鈣鈦礦薄膜。在此基礎(chǔ)上,將無空穴傳輸材料的鈣鈦礦電池效率在國際上率先突破了10%。進(jìn)一步優(yōu)化鈣鈦礦薄膜的沉積,將該電池效率提高到11.4%,為當(dāng)時(shí)國際上的最高效率。(2)通過異質(zhì)結(jié)模型研究了無空穴傳輸材料鈣鈦礦電池的電荷轉(zhuǎn)移特性,發(fā)現(xiàn)該電池的電流-電壓特性完全滿足半導(dǎo)體結(jié)型模型。進(jìn)一步推得了該異質(zhì)結(jié)的理想因子A~2,表明該電池的電荷轉(zhuǎn)移特性主要由鈣鈦礦耗盡區(qū)的復(fù)合特性決定。又通過控制薄膜的沉積條件,實(shí)現(xiàn)了對(duì)鈣鈦礦薄膜空穴濃度的調(diào)控,進(jìn)而實(shí)現(xiàn)了對(duì)鈣鈦礦耗盡電勢(shì)和內(nèi)建電場(chǎng)的調(diào)控。這種載流子濃度和內(nèi)建電勢(shì)的可調(diào)控性進(jìn)一步證實(shí)該電池是典型的異質(zhì)結(jié)太陽能電池。(3)基于對(duì)鈣鈦礦電子輸運(yùn)過程的研究和理解,發(fā)現(xiàn)限制無空穴傳輸材料鈣鈦礦電池性能的主要原因在其背表面場(chǎng)的缺失。這種缺失會(huì)導(dǎo)致部分光生電子會(huì)通過擴(kuò)散的方式自發(fā)地轉(zhuǎn)移到Au電極上,進(jìn)而與價(jià)帶的空穴進(jìn)行復(fù)合,形成嚴(yán)重的背表面復(fù)合。為了抑制此復(fù)合,通過原子層沉積(ALD)方法在鈣鈦礦吸收層和Au電極間引入了超薄的AlOx層,最終實(shí)現(xiàn)了器件光電流和性能的顯著提升。(4)發(fā)展了脈沖調(diào)控的瞬態(tài)光電測(cè)量方法,即電泵浦-瞬態(tài)光電探測(cè)。利用該方法研究了鈣鈦礦秒的時(shí)間尺度的光電遲滯及其背后的微觀物理機(jī)制。結(jié)果表明,鈣鈦礦電池在弱電壓調(diào)控下,即可在其吸收層內(nèi)形成負(fù)的內(nèi)部電場(chǎng),并逐步演化形成正電場(chǎng)。電池在開路電壓演化過程中,亦存在該過程。進(jìn)一步通過器件模擬發(fā)現(xiàn),只有同時(shí)考慮電場(chǎng)驅(qū)動(dòng)下的離子輸運(yùn)導(dǎo)致的界面摻雜和缺陷態(tài)效應(yīng)才能完美解釋上述時(shí)間相關(guān)的微觀動(dòng)力學(xué)過程。(5)為了系統(tǒng)研究鈣鈦礦太陽能電池中的電荷輸運(yùn)和復(fù)合動(dòng)力學(xué)過程,發(fā)展了可調(diào)控的瞬態(tài)光電測(cè)量系統(tǒng),并在半導(dǎo)體輸運(yùn)模型的基礎(chǔ)上建立了適用于結(jié)型電池瞬態(tài)測(cè)量的物理模型。利用該系統(tǒng),可以直接測(cè)量太陽能電池在其實(shí)際工作狀態(tài)下(不同偏壓和不同光照)的電荷輸運(yùn)和復(fù)合特性。進(jìn)一步利用物理模型,可以定量地獲得電池不同界面的電荷抽取和收集效率,從而為定性和定量研究器件性能及其物理機(jī)制奠定了技術(shù)基礎(chǔ)。
[Abstract]:Solar photovoltaic technology is one of the important means to solve the energy and environmental issues have become more serious at present, to optimize energy structure, improve environment and promote the sustainable development of great significance. The development of lower cost, more efficient solar cells has been a hot research. The photovoltaic solar cell has experienced the first generation to the second generation of crystal silicon, GaAs Heterojunction chalcogenide until the current junction thin film based on the third generation of novel thin film solar cells, new materials and new working mechanism. The perovskite cell is a new photovoltaic device was developed in recent years and has been developing rapidly. The liquid phase deposition of perovskite (such as methylamine lead iodine (CH_3NH_3PbI_3), Pb (CH formamidine iodine (NH_2) _2PbI_3) and alloy compounds) polycrystalline films have high optical absorption coefficients (105 cm-1), low defect concentration (1016 cm-3) and long carrier diffusion length. Based on these excellent The performance of high quality semiconductor, thin film deposition and the realization of the device structure and interface control, photoelectric conversion efficiency of small area perovskite battery was increased to 22.1% in just a few years, and the polysilicon business, copper indium gallium selenide and cadmium telluride cell. However, the battery is still facing perovskite stability and industrialization the area of production and many other challenges. At the same time, in the development process of the perovskite cell, the essential attribute of the materials and devices (non VS exciton exciton, sensitized VS heterojunction) and abnormal photoelectric hysteresis behavior and physical mechanisms are controversial. Based on this, we from the electronic and ionic charge battery of basic dynamics the physical properties of the device and research, and obtained the high performance of the device through the charge dynamic regulation and other means, the research results obtained as follows: (1) by means of two times recrystallization Smooth and dense PbI_2 films were prepared, and finally got the Perovskite Thin Films of high quality. On this basis, the perovskite cell efficiency will hole transport materials in the first international breakthrough to further optimize the deposition of 10%. Perovskite Thin Films, will improve the efficiency of the battery to 11.4%, then the international highest efficiency (2.) by heterojunction model of charge hole transport material perovskite cell transfer characteristic, found that the current voltage characteristics fully meet the semiconductor junction model. The ideal factor A~2 further deduced the heterojunction, showed that the composite decided mainly by the characteristics of the battery charge perovskite depletion region transfer characteristics. Through deposition condition control film, realizes the control of Perovskite Thin film hole concentration, and then realize the depletion potential and electric field in the construction control of the current Zi Nong perovskite. And the built in potential regulation to further confirm that the battery is typical of the heterojunction solar cells. (3) the research and understanding of the perovskite electronic transport process based on restrictions found the main reasons of perovskite battery performance of hole transporting materials on the back surface field is missing. This loss will lead to part of the photogenerated electrons through the diffusion spontaneously transfer to the Au electrode, and the hole in the valence band compound, to form a serious back surface recombination. In order to suppress this compound, by atomic layer deposition (ALD) method and Au electrode layer between the introduction of AlOx ultrathin layer absorption in perovskite, finally achieved significantly improve the optical device the current and performance. (4) developed transient photoelectric measuring method of pulse control, electric pump transient photoelectric detection of perovskite second time scale by the method and the back of the micro optical retardation The concept of physical mechanism. The results show that the perovskite cell in the weak voltage regulation, can be in the absorption layer to form the internal electric field of negative, and gradually formed a positive electric field. The battery open circuit voltage in the process of evolution, there is also the process. Further simulations are found only when considering the electric field driven ion transport lead interface defects and doping effect can perfectly explain the state time microscopic dynamics related. (5) in order to charge system of perovskite solar cells in the transport and recombination kinetics, the transient development of photoelectric measuring system can be controlled, and the physical model of the semiconductor transport models were formulated based on established node battery transient measurement. Using this system, it can directly measure the solar cell in the actual working conditions (different bias and different illumination) of the charge transport and recombination. Further, using physical models, we can quantitatively get the charge extraction and collection efficiency of different interfaces of batteries, thus laying a technical foundation for qualitative and quantitative research of device performance and physical mechanism.

【學(xué)位授予單位】：中國科學(xué)院大學(xué)(中國科學(xué)院物理研究所)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：TM914.4

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