Research On Broadening The Spectral Response Range Of Perovskite Solar Cells Based On Optical Engineering

Organic-inorganic halide perovskite materials（ABX₃）own the advantages of freely tunable components,high carrier mobility,large light absorption coefficient,simple preparation method,and low production cost ect.Organic-inorganic halide perovskite materials have achieved a series of breakthroughs in photovoltaic applications.Since the first application of perovskite materials in the photovoltaic field in 2009,the photoelectric conversion efficiency（PCE）of lead-based perovskite solar cells（PSCs）has been rapidly improved from the initial 3.8%to 25.7%.Despite,traditional PSCs have low utilization ability for 300-400 nm UV light,and cannot harvest 800-2500 nm infrared light in the solar spectrum,which have become the fatal shortcomings to limit the further improvement of PCE.During my Ph.D.,The main purpose of my research is to broaden the spectral response range of PSCs in the near-infrared region and to improve the utilization of PSCs for ultraviolet light in the solar spectrum.Our results demonstrate that efficient and stable PSCs with high spectral efficiency can be achieved by the strategy of introducing down-conversion fluorescent materials,near-infrared organic heterojunctions,and infrared quantum dots into the device.（1）Near-infrared copper indium gallium selenium quantum dots（CIGSe QDs）and gold nanorods（AuNRs）with plasmon resonance capability were simultaneously introduced into the hole transport layer.CIGSe QDs broadened the spectral response of PSCs to 920 nm.The AuNRs further enhanced the CIGSe QDs near-infrared absorption capability in the solar spectrum by enlarging the strength of the local optical field surrounding the CIGSe QDs.Na YF₄:Ce,Tb@Na YF₄ with the ability of energy down-conversion,light scattering center and interface modification was successfully introduced between the electron transport layer and the perovskite layer.Na YF₄:（20%）Ce,（2%）Tb@Na YF₄ nanocrystals improved the spectral responsiveness of PSCs in the ultraviolet and visible light regions（300-650 nm）.The modified PSC devices also demonstrated highly improved ultraviolet stability and long-term stability.The champion device achieved a PCE of 22.6%.（2）In order to solve the problems of low absorption coefficient of CIGSe QDs and a small amount of doped hole transport layer.Organic polymer donor PM6 and non-fullerene acceptor Y18 were prepared as organic heterojunction（BHJ）film directly deposited on the surface of the perovskite active layer,which constructed an integrated perovskite solar cell（IPSCs）devices with infrared absorption capability. PM6:Y18 broadened the spectral response range of PSCs devices to 950 nm（40% IPCE response in the near-infrared part）.A buffer layer prepared by blending polymethyl methacrylate（PMMA）,gold nanorods and functionalized single-walled carbon nanotubes was successfully introduced into the BHJ layer and the Spiro-OMe TAD layer to construct a double hole transport layer structure.Double hole transport layer structure reduced open circuit voltage and fill factor loss.The champion device achieved a PCE of 22.82%.（3）In order to further solve the problem of interfacial carrier recombination and extraction caused by the introduction of organic heterojunctions.We prepared PM6:BTP-4Cl-12 organic heterojunction films to broaden the near-infrared absorption of PSCs.We doped black phosphorus quantum dots with bipolar and high mobility properties into perovskite and organic heterojunction films to enhance the carrier extraction capability of organic heterojunction and perovskite films.Then we introduced P-type cuprous oxide with excellent hole mobility and matching ionization potential into the device as a buffer layer,which reduced the carrier recombination between the organic heterojunction layer and the hole transport layer interface and improved the overall performance of the device.The champion device achieved a PCE of 23.52%.After 3600 hours of aging,the unpackaged device still maintained 85.2%of initial efficiency.（4）Finally,In order to obtain PSCs with broad UV-Vis-NIR spectral responses,PTB7-Th:IEICO-4Cl organic heterojunction film were prepared,which further broadened the spectral response range of PSCs to 1050 nm.Then,we introduced the Nb₂CT_x quantum dots whose surface end groups were treated by UV plasma into the organic heterojunction film,which promoted the dissociation of excitons inside the films.The quantum cutting material Cs Pb Cl₃:Yb,Li quantum dots with down-conversion PLQY up to 170%are introduced into the incident light surface of the device,which enhances the utilization rate of ultraviolet light by the device.Finally,a PCE of 23.95%was obtained,which is the highest efficiency of organic heterojunction integrated perovskite cells so far.After 500 hours of UV irradiation,The PSCs device can still maintain 91%of the initial efficiency.