纳米墨水法制备高效Sb2(S,Se)3太阳能电池

Sb2S3 is a particularly attractive candidate as a light absorbing material in solar cells owing to its high absorption coefficient, simple chemistry, low melting point, extremely low toxicity, low price, as well as relative abundance of its elements, which has obtained a photon-to-electron energy conversion efficiency of 6.3% reported in the literature. However, the large band gap of Sb2S3 (1.8eV) restricts the absorption of the solar spectrum, leading to the difficulty in enhancing the device efficiency. This project is proposed to use Sb2(S,Se)3 as the light absorber in the solar cell, which provides an effective way to finely tune the bandgap ranging from 1 to 1.8eV by controlling the S/Se ratio of the alloyed Sb2(S,Se)3, thus achieving a theoretical efficiency >30% for single junction solar cells. The fabrication of high efficiency Sb2(S,Se)3 photovoltaic devices utilizes an inexpensive nano-ink based method, which has not been reported to build Sb2(S,Se)3 thin films by this method. The Sb2(S,Se)3 nano-inks with controllable composition can be synthesized by a solution process. Sb2(S,Se)3 films will be obtained by spin-coating or blade-coating methods followed by exchanging the organic ligands on the surface of the Sb2(S,Se)3 nanoparticles by inorganic ligands. Further, by optimizing heat treatment conditions, the large densely packed grains, phase-pure, high carrier mobility, low defect density of Sb2(S,Se)3 thin films can be obtained, extending the absorption of the solar spectrum to the near-IR region. Through systematic material and device optimization, we aim to obtain a Sb2(S,Se)3 solar cell with 8% efficiency.

Sb2S3材料具有吸光系数大，化学组成简单，长晶温度低，原材料储量丰富、环境友好及价格低廉等优势，同时已有文献报道效率为6.3%的太阳能电池，显示其作为电池吸收层材料的巨大应用潜力。但Sb2S3的禁带宽度为1.8eV，吸光受限制约了其器件效率的进一步提升。本项目提出以Sb2(S,Se)3作为电池吸光层材料，禁带宽度在1-1.8eV范围内连续可调，单结电池理论转换效率可达到30%以上。器件工艺选用具有低成本优势且在此体系尚未被探索的纳米粒子墨水成膜法，通过溶液合成组分可控的Sb2(S,Se)3纳米墨水，旋凃或刮涂成膜，经无机配体交换去除纳米颗粒表面有机配体，进一步热处理获得纯相大晶、高迁移率、低缺陷的Sb2(S,Se)3吸收层薄膜，拓展光谱吸收范围，最终通过材料和器件的系统优化，得到光电转换效率达8%的Sb2(S,Se)3太阳能电池。

鉴于Sb2S3禁带宽度(1.8 eV)偏大，吸光受限制约了其器件进一步提升的弊端，本项目选取Sb2(S,Se)3为太阳能电池吸光层材料，该材料禁带宽度在1-1.8 eV范围内连续可调，同时吸光系数大，长晶温度低，原材料储量丰富、环境友好及价格低廉，是有潜力的新一代太阳能电池材料。在本项目执行的三年里，申请人的主要工作进展如下：1) 采用肼溶液法制备合成了Sb-S和Sb-Se肼溶液，通过Raman光谱系统研究了Sb在肼溶液中的溶解机理，并基于该前驱体溶液制备得到了组分精确可控、禁带宽度连续可调的Sb2(S1-xSex)3 (0≤x≤1)合金薄膜，为下一步的器件制备提供有力基础；2) 采用绿色无毒的水为溶剂，常温常压下制备合成了Sb-S和Sb-Se金属硫族配位化合物(MCCs)水溶液，通过易产业化的喷雾热解方式，得到致密连续、组分可控、禁带宽度可调的Sb2(S1-xSex)3 (0≤x≤1)合金薄膜，并以此薄膜构筑了Sb2(S,Se)3吸收层太阳能电池器件；3) 在本课题组前期自主开发的快速蒸发法制备Sb2Se3薄膜的基础上，通过在制备过程中原位引入硫蒸汽，实现了Sb2(S1-xSex)3 (0≤x≤1)合金薄膜的制备，基于该薄膜最终得到器件转换效率高达5.79%的太阳能电池，为目前该类器件的最高效率；4) 在器件的系统优化方面，通过控制基底温度调控Sb2Se3薄膜的晶粒生长取向，从“横躺”取向调控为“站立”取向，一方面实现了光生载流子的高效传输，另一方面实现了一维带状晶体特有的良性晶界特点，最终得到了Newport认证效率为5.6%的太阳能电池器件。