When we have a large sample size but it caused multicollinearity, can I use PLS to solve this problem ?
Multicollinearity can be one of the problems for PLS. Firstly you can try to understand the root cause of the multicollinearity issue & address it e.g. identifying the duplicate independent variables / indicators & dropping them, combining the similar independent variables / indicators if make sense, recheck literature review whether the instrument for various variables / constructs are adopted / adapted correctly etc.
On the sample size for PLS, you can refer to the following book:
Hair, J. F., Hult, G. T. M., Ringle, C. & Sarstedt, M. (2013). A Primer on Partial Least Squares Structural Equation Modeling (PLS-SE). Sage Publications, Inc.
Minimal PLS sample size can be determined by:
10 times the largest number of formative indicators used to measure a single construct, or
10 times the largest number of structural path directed at a particular construct in the structural model.
Sample size does not cause multicollinearity. Possibly what you mean is that you finally got a sample size large enough that you could detect the multicollinearity that has always been present in your data.
Essentially the choice is to leave some factors out, or try to derive a new set of variables that are uncorrelated. If the problem is not too bad, then you can also consider ignoring the problem. Clearly defining "not too bad" is not easy.
I guess we are talking about Partial Least Squares regression and what you mean is that the data matrix you are trying to analyze has a higher number of variables than samples. In this case, you can definitely use PLS. PLS calculates, starting from your original descriptors, a set of new latent variables, ORTHOGONAL (I.E. INDEPENDENT), maximising the covariance between your X (predictor matrix) and your Y (response matrix). Multicollinearity is then overcome. Mind that such latent variables constitute both a good summary of X and valuable predictors of Y.