Shen QING (沈 青)

Offer Organization: Japan Society for the Promotion of Science, System Name: Grants-in-Aid for Scientific Research, Category: Fund for the Promotion of Joint International Research (Fostering Joint International Research (B)), Fund Type: -, Overall Grant Amount: - (direct: 14200000, indirect: 4260000)
鉛を含まないペロブスカイト太陽電池の高効率化が望まれている。錫系ペロブスカイトがその最も期待される候補であるが効率が低いという問題点があった。錫系ペロブスカイト太陽電池の効率を向上するためには結晶欠陥に起因する電荷再結合サイト密度を低下させる必要がある。これまで我々はヨウ素イオン欠陥（undercordinated Sn ion）密度を低下させるために、エチレンジアミンによるパッシベーションが有効であることを示してきた。今回表面撥水性を有するハロゲン化ケイ素(Me3Si-Br)で表面をパッシベーションしたところ、耐久性、効率が向上することを見出した。効率は表面パッシベーション後に10.05%から12.22%に向上した。耐久性は未封止、窒素下で保存したところ、パッシベーション前には40日で30%の効率低下があったが、パッシベーション後は92日間で20%の低下に抑えることができた。ヨウ素イオン欠陥にBrイオンが配位しMe3Siグループが界面、粒界に吸着することにより、ヨウ素イオン欠陥密度を低下させるとともに、粒界を疎水性化し水分の侵入を防止していると推定された。Ms3SiXのXはClイオン=Iイオン

Offer Organization: 日本学術振興会, System Name: 科学研究費助成事業, Category: 基盤研究(C), Fund Type: -, Overall Grant Amount: - (direct: 3700000, indirect: 1110000)
半導体量子ドット(QD)は太陽電池の増感剤として、色素系を凌駕する特性を持つ。従来の増感型太陽電池ではQDの吸着面積を増大させるために、基板電極としてはナノ粒子集合体酸化物が対象となる(TiO2, ZnO等)。しかしこの電極系は乱雑な多結晶体のために、QDの電子状態や電子移動に関する評価が曖昧になる。本研究は物性が十分に判明されている単結晶基板を対象として、異なる面方位を持つ酸化物単結晶へQD吸着を行い、QDに対する基板の効果を明らかにすることを目的とする。今年度も引き続きルチル型TiO2単結晶の(001), (110), (111)面を対象基板として、さらに３種類の異なる配位子をPbS-QDに結合しQD-QD間の距離の制御を行い、昨年度に得られた結果の再現性について検討を行った。従来と同様に、(1)光音響法(PA)による脱励起状態、(2)吸光度法(Abs)による励起、(3)光電子収量法(PY)によるイオン化エネルギー、の一連の再現性評価を行った。その結果、PAスペクトルとAbsスペクトルの吸収端下の異なることが再確認された。特に(111)基板上ではQD-QD間隔の増大に大きな変化が生じた、これらの結果は脱励起に伴う無輻射緩和による熱生成効率がQD-QD間隔および基板結晶面により異なるという新しい発見につながった。これらの基板情報は、従来の酸化物ナノ粒子集合体電極に対して、増感型太陽電池のエネルギー変換効率向上化を考慮するデバイス設計に対して有用な情報を提供することが可能となると考えられる。

Offer Organization: Japan Society for the Promotion of Science, System Name: Grants-in-Aid for Scientific Research, Category: Grant-in-Aid for Scientific Research (B), Fund Type: -, Overall Grant Amount: - (direct: 13300000, indirect: 3990000)
The purpose of this research is to propose the way to enhance the efficiency of Pb free perovskite solar cells, namely, Sn PVK solar cells. Focus was put on decreasing defect density of PVK crystals including the grain boundary and the heterointerfaces. In order to make clear the performance of Sn PVK layer, no metal dopant was added in B site of ABX3 structure. We aimed at unveiling items retarding the efficiency-enhancement for the Sn-PVK. We found the following items for the efficiency enhancement. 1. Inverted structures are recommended to avoid the direct contact between Sn-PVK and inorganic oxide semiconductors, 2. To reduce the crystal lattice strain by optimizing the size of A site gives higher efficiency, 3. Grain boundary passivation is effective, 4. Addition of reducing agents, such as Sm ion, are useful because of the decrease in the defect density associated with Sn4+.

Offer Organization: Japan Society for the Promotion of Science, System Name: Grants-in-Aid for Scientific Research, Category: Grant-in-Aid for Young Scientists (B), Fund Type: -, Overall Grant Amount: - (direct: 3100000, indirect: 930000)
Focus has been directed for tin-based perovskite films as a substitute for most widely studied lead halide perovskites. This research has investigated the relationship between crystal growth control of tin-based perovskite along with defect analysis and its implications on the solar cell performance.
We have demonstrated a profound enhancement of the short circuit current from 20 mA/cm2 to 30 mA/cm2 using SnI2 complex for the fabrication of tin-halide perovskite as material. It has been found that when TiO2 as electron transporting material and SnI2 were chemically bonded, there was an increase in the TiO2 surface traps. Therefore, efforts were directed to prepare the tin-based perovskite solar cells without using TiO2 which led to the improved device performance. The absorption wavelength was changed by partially replacing the iodine by bromine. SnF2 was also doped in order to supplement metal defects. The conversion efficiency of the solar cell improved from 4.5% to 15.9%.

Offer Organization: Japan Society for the Promotion of Science, System Name: Grants-in-Aid for Scientific Research, Category: Grant-in-Aid for Scientific Research (B), Fund Type: -, Overall Grant Amount: - (direct: 12900000, indirect: 3870000)
As one candidate of the next generation solar cells, colloidal quantum dot (CQD) based solar cells (CQDSCs) have attracted considerable interest and developed rapidly during the last few years. CQDSCs have some unique advantages such as the band-gap tunability, high absorption coefficient, multiple exciton generation (MEG) possibility and low cost for preparation. Although theoretical energy conversion efficiency of CQDSCs has been predicted to be about 44% much higher than the Shockley-Queisser limit (33%), it is still about 8% at present time (2014). Therefore, fundamental studies on the mechanism for improving energy conversion efficiency of CQDSCs are very important. In this project, we focus on clarifying the photoexcited carrier dynamics, especially the dynamics of MEG and improving the charge separation and suppress recombination in QD heterojunction solar cells by controlling the interfaces of CQDSCs as well as the approaches to improving the energy conversion efficiency.

Offer Organization: Japan Society for the Promotion of Science, System Name: Grants-in-Aid for Scientific Research, Category: Grant-in-Aid for Scientific Research (C), Fund Type: -, Overall Grant Amount: - (direct: 3800000, indirect: 1140000)
Quantum dots (QDs) provide an attractive alternative sensitizer to organic dyes. There is a lack of fundamental studies of QD on conventional nanocrystalline TiO2 electrodes with much amount of heteroigeneity. We have shown the dependences of the optical absorption, the ground state energy level, and interfacial electron transfer dynamics on the size of CdSe QDs on single crystal rutile-TiO2. The expenential optical absorption tail indicates a decrease in structural disorder with increasing size. The ground state energy level of the CdSe QDs shows anisotropic, depending on the surface orientation of TiO2. The interfacial electron transfer rate constant decreases with increasing size and depends on the surface orientation of TiO2.